IFRS 15 Contract Modification: Rules, Routes and Examples

1. What counts as a contract modification under IFRS 15?

A change in the scope of a contract, or its price, or both, that the parties have approved. Approval does not have to be a signed document. IFRS 15.18 accepts written agreement, oral agreement, or approval implied by customary business practice, provided the change creates new or changes existing enforceable rights and obligations. Until that approval exists, the entity keeps accounting for the contract it already has.

"A contract modification is a change in the scope or price (or both) of a contract that is approved by the parties to the contract. In some industries and jurisdictions, a contract modification may be described as a change order, a variation or an amendment. A contract modification exists when the parties to a contract approve a modification that either creates new or changes existing enforceable rights and obligations of the parties to the contract. A contract modification could be approved in writing, by oral agreement or implied by customary business practices. If the parties to the contract have not approved a contract modification, an entity shall continue to apply this Standard to the existing contract until the contract modification is approved."

Three things sit inside that paragraph and each of them causes trouble in practice.

The first is that the trigger is approval, not documentation. Finance teams almost universally use the signed variation order as the accounting event because it is the auditable artefact. The standard does not. If the site team has instructed additional work, the customer's project manager has accepted it, and both parties are behaving as though the change is binding, an IFRS 15 contract modification exists from that date even though the paperwork catches up two months later. Where a jurisdiction's contract law gives effect to oral variations, or where an entity has a long history of performing on emailed instructions and being paid, the customary business practice limb of IFRS 15.18 is doing real work.

The second is that the change must touch enforceable rights and obligations. A revised delivery schedule that neither party can enforce is not a modification. A budget reforecast is not a modification. A change in the entity's own expectation of cost is not a modification. Only a change to what the parties can legally require of one another qualifies, and IFRS 15.18 tells the entity to consider all relevant facts and circumstances including the terms of the contract and other evidence when deciding whether the changed rights are enforceable.

The third is the closing sentence. If there is no approval, the answer is not "wait and see". The answer is that the existing contract continues to be accounted for exactly as before. That matters because the practical instinct on a disputed instruction is to stop recognising revenue until the position clears, and that instinct is wrong in both directions. Before approval, keep going on the old terms. After approval, move immediately.

Read that alongside IFRS 15.18 and the picture becomes sharper. Dispute does not prevent a modification from existing. What prevents a modification from existing is the absence of approved, enforceable change. A contractor and an employer can be in adjudication over the value of a variation while both accept that the variation was instructed and carried out. That is an existing modification with an unresolved price, which is exactly the territory of the rest of IFRS 15.19.

The four possible outcomes

Once a modification exists, IFRS 15 offers exactly four destinations and the entity does not choose between them. IFRS 15.20 tests whether the change is a wholly separate contract. If it is not, IFRS 15.21 splits into three: prospective treatment under 21(a), a cumulative catch-up under 21(b), or a combination under 21(c). The table below is the whole of the standard's contract modification guidance compressed into one view, and the rest of this article expands each row.

Route	Paragraph	Condition	Effect on revenue already recognised	Effect going forward
1. Separate contract	IFRS 15.20	Added goods or services are distinct and price increases by adjusted stand-alone selling price	None. Untouched.	Original contract continues on its original terms. The addition is accounted for as a second, independent contract.
2a. Termination and replacement	IFRS 15.21(a)	Remaining goods or services are distinct from those already transferred	None. Untouched.	Unrecognised original consideration plus modification consideration is pooled and allocated across the remaining obligations. A blended rate.
2b. Continuation	IFRS 15.21(b)	Remaining goods or services are not distinct and form part of a single partially satisfied obligation	Adjusted. A cumulative catch-up to revenue at the date of modification.	Recognition continues on the remeasured progress of the whole, single obligation.
2c. Hybrid	IFRS 15.21(c)	The remaining items are a combination of the two	Adjusted for the non-distinct part only.	Split the modification and apply 21(a) and 21(b) to the respective parts, consistently with the objectives of paragraph 21.

The IFRS 15 contract modification decision tree. Every modification lands in exactly one of the four shaded boxes, and the route is determined by the facts, not by policy choice.

Practitioner note

The single most useful control I have seen on this is a variation register that captures three dates rather than one: the date of instruction, the date both parties behaved as if bound, and the date of the signed variation order. Most entities capture only the third. IFRS 15.18 usually bites on the second, and the gap between the second and the third is where cut-off errors live. On a December year end that gap is frequently the difference between a modification recognised in the current year and one recognised in the next.

Warning. A contract modification is not the same as a contract combination. IFRS 15.17 combines two or more contracts entered into at or near the same time with the same customer where the criteria in that paragraph are met, and the combined contract is then a single contract from inception. A modification changes an existing contract from the modification date forward. Combining a later order with an earlier one when the criteria in IFRS 15.17 are not met produces a retrospective distortion that the modification guidance never intended.

Local FAQs

Does an unsigned instruction create a modification?

It can. IFRS 15.18 permits approval in writing, by oral agreement or implied by customary business practices. The test is whether enforceable rights and obligations have been created or changed, considering all relevant facts and circumstances including the terms of the contract and other evidence. An instruction that the contract itself makes binding on issue is approved for IFRS 15.18 purposes on the date it is issued.

The customer disputes the value of an instructed variation. Is there a modification?

Yes, if the scope change itself is approved. IFRS 15.19 states expressly that a modification may exist even though the parties have a dispute about the scope or price, or both. The dispute goes to measurement under IFRS 15.19 and the constraint in IFRS 15.56 to 58, not to existence.

Does a change in our own cost estimate count?

No. IFRS 15.18 requires a change in the scope or price of the contract approved by the parties. A revised internal cost forecast changes neither. For a contract measured on a cost-to-cost input method it changes the measure of progress, which IFRS 15.43 treats as a change in accounting estimate under IAS 8, not as a modification.

Potential risks

Late recognition of the modification event. Using the signed variation order as the accounting trigger systematically pushes modifications into the wrong period where the parties were already bound. This is a cut-off risk, and it is directional because commercial teams sign paperwork after the work, not before.
Treating dispute as non-existence. Suspending all accounting for an instructed variation because the value is contested contradicts IFRS 15.19 and understates revenue.
Confusing enforceability with collectability. Whether the entity will be paid is a IFRS 15.9(e) and IFRS 15.56 question. Whether the rights changed is an IFRS 15.18 question. Answering the first when the standard asks the second sends the modification down the wrong route entirely.

2. What happens when the scope is approved but the price is not?

IFRS 15.19 forces an estimate. Where the parties have agreed a change in scope but have not yet fixed the money, the entity estimates the change to the transaction price using the variable consideration guidance in IFRS 15.50 to 54 and then constrains it under IFRS 15.56 to 58. Only the constrained amount enters the transaction price. Recognising nothing until settlement, and recognising the full claimed amount, are both wrong.

"A contract modification may exist even though the parties to the contract have a dispute about the scope or price (or both) of the modification or the parties have approved a change in the scope of the contract but have not yet determined the corresponding change in price. In determining whether the rights and obligations that are created or changed by a modification are enforceable, an entity shall consider all relevant facts and circumstances including the terms of the contract and other evidence. If the parties to a contract have approved a change in the scope of the contract but have not yet determined the corresponding change in price, an entity shall estimate the change to the transaction price arising from the modification in accordance with paragraphs 50 to 54 on estimating variable consideration and paragraphs 56 to 58 on constraining estimates of variable consideration."

The structure of that final sentence is worth reading slowly. It is a two-stage instruction. Stage one is estimation. Stage two is constraint. Practitioners who skip stage two report the claim. Practitioners who skip stage one report nothing. Both are defective, and they fail in opposite directions, which is why a portfolio of contractors can look wildly inconsistent on the same commercial facts.

Stage one: estimating the price change

IFRS 15.53 offers two methods and requires the entity to use the one it expects will better predict the amount of consideration to which it will be entitled. The expected value method sums probability-weighted amounts across a range of possible outcomes and suits an entity with a large number of contracts with similar characteristics. The most likely amount method picks the single most likely outcome and suits a contract with only two possible outcomes. IFRS 15.54 then requires the method to be applied consistently throughout the contract, and requires the entity to consider all reasonably available historical, current and forecast information, noting that this information would typically be similar to what management uses in the bid and proposal process and in setting prices.

For change orders, that pushes most entities towards expected value, because a negotiated variation rarely has a binary outcome. It has a claimed amount, a certified amount, an internal walk-away amount, and a plausible settlement band. The IFRS 15.54 consistency requirement is the one most often breached: an entity that used expected value on the first three variations cannot switch to most likely amount on the fourth because the fourth is going badly. Further detail on both methods sits in the variable consideration spoke.

"An entity shall include in the transaction price some or all of an amount of variable consideration estimated in accordance with paragraph 53 only to the extent that it is highly probable that a significant reversal in the amount of cumulative revenue recognised will not occur when the uncertainty associated with the variable consideration is subsequently resolved."

Two features of this wording control the answer on claims. First, the test is on cumulative revenue recognised, not on the claim in isolation. A CU 2 million uncertainty on a CU 400 million contract does not carry the same reversal risk as the same uncertainty on a CU 6 million contract, and the constraint is sensitive to that. Second, the phrase is "some or all". The constraint is not a gate that admits the whole estimate or nothing. It is a dial. The correct output of IFRS 15.56 is frequently a number that is neither the claim nor zero, and an entity that only ever produces one of those two answers is almost certainly not applying the paragraph.

"In assessing whether it is highly probable that a significant reversal in the amount of cumulative revenue recognised will not occur once the uncertainty related to the variable consideration is subsequently resolved, an entity shall consider both the likelihood and the magnitude of the revenue reversal. Factors that could increase the likelihood or the magnitude of a revenue reversal include, but are not limited to, any of the following: (a) the amount of consideration is highly susceptible to factors outside the entity's influence. Those factors may include volatility in a market, the judgement or actions of third parties, weather conditions and a high risk of obsolescence of the promised good or service. (b) the uncertainty about the amount of consideration is not expected to be resolved for a long period of time. (c) the entity's experience (or other evidence) with similar types of contracts is limited, or that experience (or other evidence) has limited predictive value. (d) the entity has a practice of either offering a broad range of price concessions or changing the payment terms and conditions of similar contracts in similar circumstances. (e) the contract has a large number and broad range of possible consideration amounts."

Construction and engineering claims tick almost every one of these. A disputed variation resolved by an engineer's certificate, an adjudicator or a court is squarely within IFRS 15.57(a), because it turns on the judgement or actions of third parties. Major claims routinely run for years, which is IFRS 15.57(b). And the settlement band on a prolongation or disruption claim is wide, which is IFRS 15.57(e). That is why a claim is the hardest version of the IFRS 15.19 problem: the paragraph tells you to estimate, and the five factors in IFRS 15.57 tell you that almost every input to that estimate is unreliable.

Why claims are the hardest case

A straightforward variation, priced from a schedule of rates and certified in the next valuation, is easy. Scope agreed, price effectively determined within days, IFRS 15.19 barely engages. The difficulty is with the population that sits between an agreed variation and a pure legal dispute: the instructed work that has been done, that the customer has not denied instructing, and where the value is contested. Four features of that population make it hard.

The scope and the price are entangled. Employers frequently argue that the instructed work was always within the original scope, which is simultaneously an argument that there is no modification and an argument that there is no additional money. Under IFRS 15.18 the entity has to reach a conclusion on enforceable rights before it can measure anything.
Cost recovery and price are not the same figure. A claim for disruption recovers cost that has already been incurred, and often already expensed. Including the claim in the transaction price under IFRS 15.19 increases revenue, but if the contract is measured on a cost-to-cost basis the additional cost has also already increased the measure of progress. The two effects interact, and the net catch-up under IFRS 15.21(b) can be positive or negative depending on whether the claimed amount carries margin relative to the contract as a whole.
The constraint is assessed at the contract level. IFRS 15.56 refers to a significant reversal in cumulative revenue recognised. On a contract that is 90 per cent complete, almost the entire uplift from a claim is recognised immediately through the catch-up mechanism, so the same claim carries a much higher reversal risk late in a contract than early in it. Entities that apply a fixed percentage haircut to all claims are not applying IFRS 15.56.
Settlement is usually a package. Claims settle in bundles, with a single number covering several variations, an extension of time and a release of counterclaims. Allocating a global settlement back to the individual modifications is a judgement that IFRS 15 does not address directly and that has to be made on a reasonable and consistently applied basis.

Balfour Beatty plc

Balfour Beatty's accounting policy for revenue on construction contracts addresses variations and claims directly. The group explains that amounts arising from variations, compensation events and claims are included in the contract transaction price only to the extent that it is highly probable that a significant reversal of cumulative revenue will not occur, which is the constraint in IFRS 15.56. The group also identifies the estimation of contract revenue, including the recovery of variations and claims, as an area of significant judgement and estimation uncertainty, and describes the internal contract review process by which those estimates are challenged.

The disclosure is a useful model because it separates the two stages IFRS 15.19 requires. It describes how the amounts are estimated, and separately how the constraint is applied to them. Many contractor policies describe only the second, which leaves a reader unable to tell whether the entity is estimating a settlement band at all.

Balfour Beatty plc, Annual Report and Accounts 2023, revenue accounting policy and critical accounting judgements and key sources of estimation uncertainty.

Practitioner note

My view: the most defensible claims estimates I have audited were built bottom up from the entity's own commercial position rather than top down from the claimed amount. The claimed number is a negotiating position and is a poor starting point for an IFRS 15.53 estimate, because it is deliberately set above the expected settlement. Where the entity's internal commercial assessment, its external legal advice and its historical settlement rates on similar claims all point at a band, the constrained amount under IFRS 15.56 should normally sit at or below the bottom of that band, not at its midpoint. If an entity's claims are settling on average at 55 per cent of the amounts it has recognised, the constraint is not working.

Warning. IFRS 15.19 does not permit an entity to recognise revenue on work it has performed where the change in scope has not been approved. A contractor that proceeds at risk on an instruction the employer denies giving has no approved modification under IFRS 15.18, and therefore nothing to estimate under IFRS 15.19. The costs still exist and are assessed under IFRS 15.98(b), which requires costs of wasted materials, labour or other resources to fulfil the contract that were not reflected in the price of the contract to be expensed as incurred. Where the outcome of the whole contract has become loss making, IAS 37.66 to 69 on onerous contracts applies, and IAS 37.68A, effective for periods beginning on or after 1 January 2022, confirms that the cost of fulfilling a contract comprises the costs that relate directly to the contract.

Local FAQs

Can we recognise a claim at zero and disclose it instead?

Only if the constrained estimate under IFRS 15.56 is genuinely nil. A blanket policy of recognising claims at nil until settlement is not an application of IFRS 15.19, which requires an estimate. Where the constrained amount is nil, IFRS 15.122 requires the entity to explain qualitatively whether consideration is not included in the transaction price and therefore excluded from the remaining performance obligation disclosure under IFRS 15.120.

Does the constraint reset each period?

Yes. IFRS 15.59 requires the entity at the end of each reporting period to update the estimated transaction price, including updating its assessment of whether an estimate of variable consideration is constrained, to represent faithfully the circumstances present at the end of the reporting period. A claim that was constrained to nil at one year end may support a substantial amount at the next if an adjudication decision or an interim certificate has landed.

What if the customer approves the price but not the scope?

That combination is rare but it happens on lump sum re-negotiations. IFRS 15.18 requires an approved change to scope or price or both, so an agreed price change alone is a modification. Because no distinct goods or services have been added, IFRS 15.20(a) fails immediately and the change is routed to IFRS 15.21.

Potential risks

Anchoring on the claimed amount. Using the claim as the IFRS 15.53 estimate and then applying a percentage haircut is not the same as estimating the expected settlement and constraining it. The first produces systematically high revenue.
Ignoring contract completion in the constraint. The same claim carries different reversal risk at 20 per cent complete and 90 per cent complete, because IFRS 15.56 measures reversal against cumulative revenue recognised.
Inconsistent method. Switching between expected value and most likely amount within a contract breaches IFRS 15.54 and is usually a sign that the estimate is being reverse engineered from a target.
Forgetting the disclosure. IFRS 15.123 requires disclosure of the judgements and changes in judgements that significantly affect the amount and timing of revenue, and IFRS 15.126 covers the methods, inputs and assumptions used in determining and constraining the transaction price. Claims estimates are precisely what these paragraphs are aimed at.

3. Route 1: when is an IFRS 15 contract modification a separate contract?

Only when both conditions in IFRS 15.20 hold at the same time. The scope has to increase because of added goods or services that are distinct, and the price has to increase by an amount that reflects the entity's stand-alone selling prices for those additions, adjusted for the circumstances of the particular contract. If either fails, the change is not a separate contract and IFRS 15.21 takes over. When both hold, the original contract is left entirely alone.

"An entity shall account for a contract modification as a separate contract if both of the following conditions are present: (a) the scope of the contract increases because of the addition of promised goods or services that are distinct (in accordance with paragraphs 26 to 30); and (b) the price of the contract increases by an amount of consideration that reflects the entity's stand-alone selling prices of the additional promised goods or services and any appropriate adjustments to that price to reflect the circumstances of the particular contract. For example, an entity may adjust the stand-alone selling price of an additional good or service for a discount that the customer receives, because it is not necessary for the entity to incur the selling-related costs that it would incur when selling a similar good or service to a new customer."

Note what the paragraph does not say. It does not say the price has to equal the list price. It does not say the addition has to be on identical commercial terms to the original. It says the increase must reflect stand-alone selling prices with appropriate adjustments for the circumstances of the particular contract, and it gives one worked justification for a downward adjustment.

Condition (a): the addition has to be distinct

IFRS 15.20(a) sends the reader straight to the distinctness criteria. Those are set out in IFRS 15.27 and elaborated in IFRS 15.29. A good or service is distinct if the customer can benefit from it either on its own or together with other readily available resources, and if the entity's promise to transfer it is separately identifiable from the other promises in the contract. IFRS 15.29 lists the factors that indicate two or more promises are not separately identifiable: a significant integration service, significant modification or customisation, and goods or services that are highly interdependent or highly interrelated.

"A good or service that is promised to a customer is distinct if both of the following criteria are met: (a) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (ie the good or service is capable of being distinct); and (b) the entity's promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (ie the promise to transfer the good or service is distinct within the context of the contract)."

The trap in a modification context is the second criterion. Added goods or services are assessed for separate identifiability within the context of the modified contract, not in the abstract. Ten additional identical units bolted onto an order for the same units are almost always distinct. An additional treatment stage welded into a plant that the entity is already building for the same customer is almost always not, because IFRS 15.29(a) and IFRS 15.29(c) both bite. The performance obligations spoke works through the IFRS 15.27 and IFRS 15.29 analysis in detail.

Condition (b): the price has to reflect adjusted stand-alone selling price

This is the condition that fails. IFRS 15.77 defines the stand-alone selling price as the price at which an entity would sell a promised good or service separately to a customer, and states that the best evidence is the observable price when the entity sells it separately in similar circumstances and to similar customers. It also warns that a contractually stated price or list price may be, but shall not be presumed to be, the stand-alone selling price. Where the price is not directly observable, IFRS 15.78 requires an estimate, and IFRS 15.79 sets out suitable estimation methods.

The interesting phrase in IFRS 15.20(b) is "any appropriate adjustments to that price to reflect the circumstances of the particular contract". This is an allowance, not a loophole. The standard's own illustration is a discount granted because the entity avoids selling-related costs it would incur on a new customer. The logic is economic. If selling to a new customer costs the entity CU 50 per unit in sales commission, credit assessment and onboarding, and it does not incur those costs on an add-on to an existing account, then a CU 50 per unit discount does not represent a concession on the value of the goods. It represents the avoided cost of getting the order. The price still reflects stand-alone selling price for the circumstances of that contract.

Reason for a discount on the added items	Does it survive IFRS 15.20(b)?	Reasoning
Avoided selling-related costs on an existing account	Yes	This is the express example in IFRS 15.20(b). The economics of supplying the additional units differ from a new customer sale.
Volume discount the entity offers to any customer buying the same total quantity	Usually yes	If the entity would offer the same rate to a new customer at that volume, the discounted rate is the stand-alone selling price for that volume under IFRS 15.77.
Avoided delivery, mobilisation or set-up cost because the entity is already on site	Usually yes	A genuine, quantifiable circumstance of the particular contract. The adjustment should be supportable at roughly the amount of cost avoided.
Discount to persuade the customer not to move the remaining volume to a competitor	No	This is a concession on the value of the goods, not an adjustment for the circumstances of supply. IFRS 15.20(b) fails and the change goes to IFRS 15.21.
Discount because the entity performed poorly on the delivered units	No	Economically this is a price concession on goods already transferred. It is likely to be variable consideration under IFRS 15.52 rather than a modification at all.
Discount to secure a longer commitment, given across both old and new volume	No	A discount that reprices goods not yet delivered under the original order is not an adjustment to the stand-alone selling price of the additions. Blend and extend arrangements fail IFRS 15.20(b) almost by construction.

Practitioner note

My view: the discipline that makes IFRS 15.20(b) auditable is quantifying the adjustment rather than asserting it. If the entity claims a CU 400 per unit discount is justified by avoided selling costs, the file should show what those costs actually are. In my experience the avoided-cost adjustment is usually worth a low single-digit percentage of price. When an entity is arguing that a 40 per cent discount reflects avoided selling costs, the argument fails on its own arithmetic long before it fails on principle. The right answer in that case is IFRS 15.21, and the earlier the entity accepts that, the less painful the blended-price recalculation is.

What separate-contract treatment actually does

The effect is the cleanest of the four routes. The original contract carries on exactly as it was. Its transaction price does not change, its allocation does not change, and nothing already recognised moves. The addition is accounted for as if it were a fresh contract with the same customer: identify its performance obligations under IFRS 15.22, determine its transaction price under IFRS 15.47, allocate under IFRS 15.73, and recognise under IFRS 15.31. Two contracts, running in parallel, at two different unit prices.

That last point is worth pausing on because it strikes people as counter-intuitive. Under separate-contract treatment the entity can be recognising CU 1,000 per unit on the original order and CU 950 per unit on the addition, on the same day, for identical goods. That is correct and it is the point. The economics of the two orders are genuinely different, and IFRS 15.20 recognises that by ring-fencing them.

Warning. Separate-contract treatment is the treatment entities want, because it involves no recalculation and no restatement of anything. That commercial preference is exactly why IFRS 15.20 deserves the most audit attention of the four routes. Where the conclusion is separate contract, the file needs evidence on both conditions. A distinctness memo alone is only half of IFRS 15.20.

Local FAQs

Can a modification that only increases price be a separate contract?

No. IFRS 15.20(a) requires the scope to increase because of the addition of promised goods or services that are distinct. A pure price increase adds nothing distinct, so condition (a) fails and IFRS 15.21 applies.

Do the added goods have to be the same as the original goods?

No. IFRS 15.20(a) requires only that they are distinct in accordance with IFRS 15.26 to 30. Adding a two-year maintenance service to a contract for equipment already delivered can meet IFRS 15.20(a) provided the service is distinct, and will be a separate contract if it is priced at its adjusted stand-alone selling price.

What if there is no observable stand-alone selling price for the addition?

IFRS 15.78 requires the entity to estimate the stand-alone selling price at an amount that would result in the allocation meeting the objective in IFRS 15.73, maximising observable inputs and applying estimation methods consistently. IFRS 15.79 lists the adjusted market assessment approach, the expected cost plus a margin approach and the residual approach. The absence of an observable price does not prevent IFRS 15.20(b) from being met, but it raises the evidential bar.

Does a modification priced above stand-alone selling price qualify?

IFRS 15.20(b) requires the price to increase by an amount that reflects stand-alone selling prices with appropriate adjustments. A premium can reflect the circumstances of the particular contract, for example expedited supply, if the entity would charge the same premium to any customer in those circumstances. A premium that exists only because the customer is captive and cannot go elsewhere does not reflect a stand-alone selling price and fails the condition.

Potential risks

Defaulting every change order to separate-contract treatment. This is the single most common error on high-volume contract portfolios, and it is usually a systems artefact. A new line on the sales order becomes a new contract in the revenue engine regardless of price.
Asserting the avoided-cost adjustment without quantifying it. IFRS 15.20(b) allows adjustments to reflect the circumstances of the particular contract. It does not allow an unmeasured assertion to justify any discount.
Treating list price as stand-alone selling price. IFRS 15.77 states that a contractually stated price or list price may be, but shall not be presumed to be, the stand-alone selling price. Where the entity habitually discounts off list, list price is not the benchmark.
Missing that a discount touches the original goods. If the modification reprices undelivered units from the original order as well as the added units, the price increase cannot be said to reflect the stand-alone selling price of the additions alone. That is a IFRS 15.21 case.

4. Route 2a: how does an IFRS 15 prospective modification work?

IFRS 15.21(a) treats the change as if the old contract had been terminated and a new one created. It applies where the goods or services still to be transferred are distinct from those already transferred. The consideration allocated to what is left is the unrecognised part of the original transaction price plus the modification consideration. Revenue already recognised is not touched, and the remaining obligations are re-priced at a blended rate from the modification date forward.

"If a contract modification is not accounted for as a separate contract in accordance with paragraph 20, an entity shall account for the promised goods or services not yet transferred at the date of the contract modification (ie the remaining promised goods or services) in whichever of the following ways is applicable: (a) An entity shall account for the contract modification as if it were a termination of the existing contract and the creation of a new contract, if the remaining goods or services are distinct from the goods or services transferred on or before the date of the contract modification. The amount of consideration to be allocated to the remaining performance obligations (or to the remaining distinct goods or services in a single performance obligation identified in accordance with paragraph 22(b)) is the sum of: (i) the consideration promised by the customer (including amounts already received from the customer) that was included in the estimate of the transaction price and that had not been recognised as revenue; and (ii) the consideration promised as part of the contract modification."

The mechanic is a pooling exercise, and it has two ingredients that people routinely get wrong.

Ingredient (i) is not the total original contract price and it is not the amount left to be invoiced. It is the consideration that was included in the estimate of the transaction price and that has not yet been recognised as revenue. Three consequences follow. Consideration that was excluded from the transaction price because it was constrained under IFRS 15.56 is not in the pool. Amounts already received in cash but not yet recognised as revenue are in the pool, which is why the paragraph says "including amounts already received from the customer". And the split between recognised and unrecognised is a revenue split, not a billing split, so an over-billed or under-billed position is irrelevant to the calculation.

Ingredient (ii) is the new money. Where the modification price itself is not yet agreed, ingredient (ii) is the IFRS 15.19 constrained estimate, not the claimed amount.

The distinctness test in IFRS 15.21 is a different test

This trips people up, so it is worth stating plainly. IFRS 15.20(a) asks whether the added goods or services are distinct. IFRS 15.21(a) asks whether the remaining goods or services are distinct from those already transferred. Different populations, different comparators, different answers.

Consider a contract to deliver 100 identical machined components. The added 40 components are distinct, so IFRS 15.20(a) is satisfied. If the price fails IFRS 15.20(b), the entity moves to IFRS 15.21 and asks a new question: are the 80 components still to be delivered distinct from the 60 already delivered? They are. Each unit is capable of being distinct under IFRS 15.27(a) and separately identifiable under IFRS 15.27(b), and none of the IFRS 15.29 factors applies. So IFRS 15.21(a) governs, prospectively.

Now consider a contract to build a wastewater treatment plant, half built. The modification adds an integrated treatment stage. IFRS 15.20(a) fails because the added stage is not distinct in the context of the contract, given the significant integration service in IFRS 15.29(a) and the interdependency in IFRS 15.29(c). The entity moves to IFRS 15.21 and asks whether the remaining construction work is distinct from the work already done. It is not. The plant is one performance obligation, partially satisfied. IFRS 15.21(b) governs, with a cumulative catch-up.

The blended rate, and why it looks wrong

The output of IFRS 15.21(a) on a units contract is a single per-unit revenue rate applied to every remaining unit regardless of which order it came from. If the original units were priced at CU 1,000 and the added units at CU 600, and 40 of each remain, the pool is CU 40,000 plus CU 24,000, and every one of the 80 remaining units is recognised at CU 800.

The commercial team will object that the entity is invoicing CU 1,000 for a unit and recognising CU 800. That is correct, and the difference is not a loss. It is a contract liability under IFRS 15.106, reflecting the fact that the entity has been paid ahead of its performance measured on the modified terms, and it unwinds as the discounted units are delivered. The mirror image also occurs: an under-billed position on the discounted units produces a contract asset under IFRS 15.107. The contract assets and liabilities spoke covers the presentation mechanics.

"If a customer pays consideration, or an entity has a right to an amount of consideration that is unconditional (ie a receivable), before the entity transfers a good or service to the customer, the entity shall present the contract as a contract liability when the payment is made or the payment is due (whichever is earlier). A contract liability is an entity's obligation to transfer goods or services to a customer for which the entity has received consideration (or an amount of consideration is due) from the customer."

Under a prospective modification the contract liability is created by the difference between contractual billing rates and the blended revenue rate, not by an advance payment in the ordinary sense. It is nonetheless a contract liability on the IFRS 15.106 definition, because the entity has an unconditional right to consideration for goods it has not yet, on the modified allocation, been treated as having transferred.

Where the remaining obligations are not all the same

The units example gives a single blended rate because the remaining obligations are identical. Where they are not, the pooled consideration has to be allocated across the remaining performance obligations on the normal basis. IFRS 15.74 requires allocation on a relative stand-alone selling price basis, and IFRS 15.76 requires the stand-alone selling price to be determined at contract inception. Under IFRS 15.21(a) the "new contract" is deemed to be created at the modification date, so the relevant stand-alone selling prices are those at the modification date, not those at the original inception. That is a real and frequently missed consequence of the termination and replacement fiction. The allocation spoke sets out the relative stand-alone selling price mechanics in full.

Practitioner note

My view: the practical failure mode with IFRS 15.21(a) is not the calculation, it is the systems. Very few revenue engines can hold a unit at one price for billing and another for revenue over an extended period, so entities end up maintaining the blended rate in a spreadsheet alongside the ledger. That works until there is a second modification, at which point the pool has to be rebuilt from the revised position, and the spreadsheet almost always rebuilds it from the original contract instead. If an entity has had more than two modifications on the same contract, the first thing worth testing is whether the second pool was built off the post-first-modification unrecognised amount or off the original transaction price.

Local FAQs

Is IFRS 15.21(a) the same as a retrospective modification?

No, it is the opposite. IFRS 15 does not use the term retrospective. What is loosely called an IFRS 15 retrospective modification is the cumulative catch-up in IFRS 15.21(b). IFRS 15.21(a) is the prospective route: nothing already recognised is adjusted, and the effect of the modification is spread over the remaining obligations only.

What if the modification reduces the price with no change in scope?

IFRS 15.20(a) fails because no distinct goods or services are added. If the remaining goods or services are distinct from those already transferred, IFRS 15.21(a) applies and the reduced total is pooled with the unrecognised original amount and spread over what is left. Nothing already recognised reverses. But first check whether the reduction is a modification at all, because IFRS 15.52 may make it variable consideration from inception.

Do we reallocate to obligations that are already fully satisfied?

No. IFRS 15.21 applies to the promised goods or services not yet transferred at the date of the modification. Satisfied obligations are outside the exercise entirely under IFRS 15.21(a).

What happens if consideration was constrained at inception?

Only the consideration that was included in the estimate of the transaction price enters the pool under IFRS 15.21(a)(i). Constrained amounts were, by definition, excluded, so they are not in the pool. If that constrained amount later becomes recognisable, IFRS 15.90(a) applies and allocates it to the performance obligations identified in the contract before the modification, to the extent it is attributable to variable consideration promised before the modification.

Potential risks

Pooling the wrong number. Using the unbilled balance, or the total original contract value, instead of the unrecognised portion of the transaction price. On a contract where billing runs ahead of or behind revenue, these are materially different figures.
Applying prospective treatment to a single non-distinct obligation. The most costly error in this area, covered in the next unit. It suppresses a catch-up that IFRS 15.21(b) requires.
Using inception-date stand-alone selling prices in the new pool. The fiction in IFRS 15.21(a) is a new contract created at the modification date, so the relative stand-alone selling prices under IFRS 15.74 are those applicable at that date.
Not rebuilding the pool on a second modification. Each successive modification under IFRS 15.21(a) starts from the position immediately before it, not from the original contract.

5. Route 2b: when does an IFRS 15 modification require a cumulative catch-up?

When the goods or services still to be transferred are not distinct and therefore form part of a single performance obligation that is only partly satisfied at the modification date. IFRS 15.21(b) treats the change as part of the existing contract. The entity remeasures the transaction price and its progress on the whole obligation, and puts the entire difference through revenue at the date of the modification, either as an increase or as a reduction.

"An entity shall account for the contract modification as if it were a part of the existing contract if the remaining goods or services are not distinct and, therefore, form part of a single performance obligation that is partially satisfied at the date of the contract modification. The effect that the contract modification has on the transaction price, and on the entity's measure of progress towards complete satisfaction of the performance obligation, is recognised as an adjustment to revenue (either as an increase in or a reduction of revenue) at the date of the contract modification (ie the adjustment to revenue is made on a cumulative catch-up basis)."

Three details in that sentence are load bearing.

The adjustment covers both the effect on the transaction price and the effect on the measure of progress. Most explanations of IFRS 15.21(b) describe only the first. In a cost-to-cost contract the second is often the larger of the two, because a modification that adds work adds cost to the denominator and therefore reduces measured progress on the whole obligation.

The adjustment can be a reduction of revenue. IFRS 15.21(b) says so explicitly. A modification that adds work at a margin below the contract's blended margin produces a debit to revenue in the period of the change even though the contract price has increased. Entities that treat a negative catch-up as an error and post it to cost of sales are misstating the revenue line.

The adjustment is made at the date of the contract modification, not at the period end and not when the paperwork is complete. Where the modification date and the reporting date fall in different periods, that distinction determines which period carries the catch-up.

The mechanics, step by step

The calculation is short and the discipline is in the sequencing. On a contract measured using an input method under IFRS 15.41 and IFRS 15.B18, the steps are:

Establish cumulative revenue recognised to the modification date. This is the number the catch-up is measured against.
Determine the modified transaction price. Original transaction price, plus the modification consideration, with any unagreed element estimated and constrained under IFRS 15.19.
Determine the revised total expected costs to complete the whole, single performance obligation, including the modification scope.
Recompute the measure of progress at the modification date: costs incurred to date divided by revised total expected costs. IFRS 15.43 confirms that updating the measure of progress as circumstances change is a change in accounting estimate under IAS 8, and the modification supplies the change in circumstances.
Multiply the modified transaction price by the recomputed progress. That is what cumulative revenue should now be.
The difference between step 5 and step 1 is the cumulative catch-up. Post it to revenue.

The direction of the catch-up follows a simple rule that is worth internalising, because it is the fastest sanity check available. If the modification carries a higher margin than the contract's blended margin, the catch-up is positive. If it carries a lower margin, the catch-up is negative. If it carries exactly the blended margin, the catch-up is nil and only the future profile changes.

"As circumstances change over time, an entity shall update its measure of progress to reflect any changes in the outcome of the performance obligation. Such changes to an entity's measure of progress shall be accounted for as a change in accounting estimate in accordance with IAS 8 Basis of Preparation of Financial Statements."

This paragraph is what makes the catch-up mechanically defensible rather than a special rule invented for modifications. Under IFRS 15.21(b) the modified contract is treated as a continuation, so the entity is simply doing what it would do on any change in estimate: applying the revised estimate to the whole obligation from the current date, with the cumulative effect in the current period. IAS 8 prohibits restating prior periods for a change in estimate, and IFRS 15.21(b) is consistent with that. The catch-up is a current-period adjustment, not a prior-period restatement.

Warning. A negative catch-up is not the same thing as an onerous contract. IFRS 15 contains no onerous contract guidance; that sits in IAS 37.66 to 69, and IAS 37.68A, effective for periods beginning on or after 1 January 2022, confirms that the cost of fulfilling a contract comprises the costs that relate directly to the contract. A modification that turns a contract loss making triggers two separate exercises: the IFRS 15.21(b) catch-up on revenue, and an IAS 37 assessment of whether the unavoidable costs of meeting the modified obligations exceed the expected economic benefits. Doing the second without the first understates revenue and overstates the provision.

Why this route is where the money is

The IFRS 15.21(b) population is small in number and large in value. It is dominated by construction, engineering, shipbuilding, defence platforms, complex software implementations and long-run outsourcing transitions: contracts where the entity provides a significant service of integrating goods and services into a combined output under IFRS 15.29(a), and therefore has one performance obligation satisfied over time. Those contracts also happen to be the ones with the most modifications. A single major infrastructure job can carry hundreds of variations.

The consequence is that IFRS 15.21(b) is applied at scale, in aggregate, through contract review meetings rather than through individual accounting entries, and the catch-up emerges as a movement in the contract position rather than as an identifiable journal. That is normal, but it makes the control environment the thing that matters. If the entity's contract review process updates the forecast cost to complete and the forecast final revenue at the same time, and the revenue system recalculates progress against both, the catch-up happens automatically and correctly. If the two are updated on different cycles, it does not. The over time versus point in time spoke covers the underlying measurement of progress in more depth.

Rolls-Royce Holdings plc

Rolls-Royce accounts for long-term service agreements on its aftermarket engine programmes as arrangements under IFRS 15 in which revenue is recognised over time. Its accounting policy explains that these contracts are subject to frequent amendments over their multi-decade lives, and that changes to contractual terms are assessed as contract modifications under IFRS 15. The group discloses that where a modification is not accounted for as a separate contract, the effect is reflected through a cumulative adjustment, and it identifies the estimation of lifetime contract revenue and costs on long-term service agreements as a key source of estimation uncertainty.

The disclosure illustrates the point about scale. On a contract with a twenty-year or thirty-year horizon, the measure of progress is a function of estimated total flying hours and total costs, so a modification that changes either changes the cumulative position immediately. The catch-up is not an exception on those contracts. It is the normal machinery.

Rolls-Royce Holdings plc, Annual Report 2023, revenue recognition accounting policy for long-term service agreements and critical accounting estimates.

BAE Systems plc

BAE Systems recognises revenue on the majority of its long-term defence contracts over time and measures progress using a cost-based input method. The group's accounting policy identifies contract accounting as an area involving significant judgement, and describes amendments to contract scope and price as part of the estimation process that drives the forecast contract outturn. The disclosures explain that changes in the estimated total contract value or total contract costs are reflected in the period in which the circumstances giving rise to the revision become known, which is the cumulative catch-up mechanism in operation.

Read against IFRS 15.21(b) and IFRS 15.43, that language does two jobs. It confirms that revisions run through the current period rather than through restatement, and it links the revenue effect to the same forecast that drives cost recognition, which is the control that makes the catch-up reliable.

BAE Systems plc, Annual Report 2023, revenue and profit recognition accounting policy and critical accounting judgements.

Local FAQs

Is the cumulative catch-up a prior period adjustment?

No. IFRS 15.21(b) requires the adjustment to revenue at the date of the contract modification, and IFRS 15.43 characterises the change in the measure of progress as a change in accounting estimate under IAS 8. Changes in estimate are recognised prospectively from the date of change, with the cumulative effect in the current period. Comparatives are not restated.

Can the catch-up be negative if the price went up?

Yes, and this surprises people. If the modification adds scope at a margin below the contract's blended margin, the additional cost dilutes the measure of progress more than the additional price lifts the transaction price, and cumulative revenue falls. IFRS 15.21(b) expressly contemplates an adjustment that is a reduction of revenue.

Which period does the catch-up belong to if the modification is approved mid-month?

The period containing the date of the modification, because IFRS 15.21(b) fixes the adjustment at that date. For a modification approved on 20 December with a 31 December year end, the catch-up is in the current year even though no invoice has issued.

Does the catch-up apply if the contract is measured with an output method?

Yes. IFRS 15.21(b) refers to the entity's measure of progress without limiting it to input methods. On an output method such as surveys of performance completed to date under IFRS 15.B15, a modification that increases the total output required reduces measured progress in the same way, and the catch-up mechanism is identical.

Potential risks

Applying prospective treatment instead. Spreading the modification over the remaining work on a single non-distinct obligation defers margin that IFRS 15.21(b) requires now, and it accumulates across successive modifications until the contract position is materially wrong.
Adjusting only the transaction price. IFRS 15.21(b) requires the effect on the measure of progress to be captured too. Updating price without updating cost to complete produces a catch-up that is directionally right and quantitatively wrong.
Timing the catch-up to the period end. IFRS 15.21(b) fixes the adjustment at the modification date. On a December modification this is a cut-off issue.
Posting a negative catch-up outside revenue. A reduction of revenue belongs in revenue. Routing it to cost of sales or to an other-income line misstates the revenue caption and distorts the gross margin disclosures.
Assuming a single performance obligation without documenting it. The whole route depends on the remaining goods or services not being distinct. That conclusion rests on IFRS 15.27 and the IFRS 15.29 factors and must be evidenced, not assumed from the contract's length.

6. Route 2c: how does the hybrid in IFRS 15.21(c) work?

IFRS 15.21(c) covers the case where some of the remaining goods or services are distinct from those already transferred and some are not. The entity splits the modification, applies IFRS 15.21(a) to the distinct part and IFRS 15.21(b) to the non-distinct part, and does so in a manner consistent with the objectives of paragraph 21. There is no separate mechanic; there is a requirement to combine the other two coherently.

"If the remaining goods or services are a combination of items (a) and (b), then the entity shall account for the effects of the modification on the unsatisfied (including partially unsatisfied) performance obligations in the modified contract in a manner that is consistent with the objectives of this paragraph."

This is the shortest of the four routes and the least prescriptive. It sets an objective rather than a method, which means the entity has to work out what the objectives of paragraph 21 are and then demonstrate that its approach meets them. Reading paragraph 21 as a whole, those objectives are: revenue already recognised on obligations that remain intact is not disturbed; the modification consideration and the unrecognised original consideration are allocated only to what is still owed; and where a partially satisfied non-distinct obligation is affected, the cumulative position on that obligation is brought to where it should be at the modification date.

When it actually arises

The hybrid is rarer than the other three but it is not exotic. It arises in three recognisable shapes.

A partly built asset plus a separate service. An entity is halfway through building a processing facility as a single performance obligation. The modification adds an integrated capacity upgrade to the facility and, at the same time, a three-year distinct maintenance service to begin at handover. The upgrade is not distinct from the remaining construction, so it goes to IFRS 15.21(b) and drives a catch-up. The maintenance service is distinct from everything already transferred, so it goes to IFRS 15.21(a), and its share of the pooled consideration is spread over the service period.

A bundled deal with a partly delivered element. A technology contract has a bespoke implementation still in progress, treated as one obligation under IFRS 15.29(a) and IFRS 15.29(b), plus undelivered licences that are distinct. A single modification changes the price of the whole and adds implementation scope. The implementation scope drives a catch-up; the licence element is repriced prospectively.

A framework where one work package is live. Under a master agreement, one statement of work is mid-delivery as a single non-distinct obligation and two future statements of work are distinct. A modification to the framework pricing affects all three. The live one takes a catch-up, the two future ones take blended prospective pricing.

How to split it defensibly

IFRS 15.21(c) gives no allocation formula, so the entity has to construct one and disclose the judgement under IFRS 15.123. The approach that holds up under challenge has three steps.

Split the modification consideration between the distinct and non-distinct populations on a relative stand-alone selling price basis. This is not required by IFRS 15.21(c) in terms, but it is the allocation objective the standard uses everywhere else, at IFRS 15.73 and IFRS 15.74, so it is the natural default and the easiest to defend as consistent with the objectives of paragraph 21.
Apply IFRS 15.21(b) to the non-distinct part first. Compute the catch-up on the partially satisfied obligation using its share of the modified transaction price and its revised measure of progress. Do this first because it fixes the amount of consideration attaching to the obligation that is being continued, which removes it from the pool available to the prospective part.
Pool the remainder and apply IFRS 15.21(a) to the distinct part. The unrecognised original consideration attributable to the distinct remaining obligations, plus their share of the modification consideration, is allocated across them on relative stand-alone selling prices at the modification date.

Practitioner note

My view: the most common mistake with IFRS 15.21(c) is not doing it at all. Faced with a modification that touches both a live non-distinct obligation and distinct future obligations, entities pick whichever of IFRS 15.21(a) or 21(b) covers the larger part and apply it to everything, on the reasoning that the standard does not prescribe a method for the hybrid so any reasonable approach will do. That is not what IFRS 15.21(c) says. It says the entity shall account for the effects on the unsatisfied obligations consistently with the objectives of paragraph 21, and applying prospective treatment to a partially satisfied non-distinct obligation is not consistent with those objectives because it suppresses the catch-up that paragraph 21(b) exists to produce. Where the split is genuinely immaterial, say so in the file and move on. Do not dress up a shortcut as a policy.

Local FAQs

Does IFRS 15.21(c) require a specific allocation method?

No. It requires the effects to be accounted for in a manner consistent with the objectives of paragraph 21. A relative stand-alone selling price split, consistent with IFRS 15.73 and IFRS 15.74, is the most readily defensible approach because it aligns with the allocation objective used throughout the standard.

Can a single modification produce both a catch-up and a blended forward rate?

Yes. That is exactly what IFRS 15.21(c) produces. The non-distinct partially satisfied obligation takes a cumulative catch-up at the modification date under IFRS 15.21(b), and the distinct remaining obligations take a re-based prospective rate under IFRS 15.21(a).

What disclosure does the hybrid attract?

IFRS 15.123 requires disclosure of the judgements and changes in judgements that significantly affect the amount and timing of revenue. The split methodology used under IFRS 15.21(c) is a judgement of exactly that kind, and where material it should be described rather than left implicit in the numbers.

Potential risks

Collapsing the hybrid into a single route. Applying one of IFRS 15.21(a) or 21(b) to the whole modification because it is simpler is a departure from IFRS 15.21(c), not an application of it.
Allocating the modification consideration arbitrarily. Splitting on cost, on headcount or on management's view without reference to the allocation objective in IFRS 15.73 invites challenge and produces inconsistent outcomes across contracts.
Double counting the consideration. The unrecognised original consideration is finite. Amounts assigned to the continuing non-distinct obligation are no longer available for the prospective pool.

7. Why does the order of the tests decide the answer?

Because each test uses a different population and a different comparator, and each one filters what reaches the next. IFRS 15.18 decides whether there is anything to account for. IFRS 15.19 fixes the amount. IFRS 15.20 decides whether the original contract is touched at all. Only if IFRS 15.20 fails does IFRS 15.21 apply, and IFRS 15.21 then asks a question that IFRS 15.20 never asked. Reversing any two of those steps produces a different number.

The five questions, in the only order that works

Step	Question	Population assessed	Consequence of a "no"
1. IFRS 15.18	Have the parties approved a change to enforceable rights or obligations, in scope or price or both?	The change itself	No modification. Keep applying IFRS 15 to the existing contract.
2. IFRS 15.19	Has the corresponding change in price been determined?	The modification consideration	Estimate it under IFRS 15.50 to 54 and constrain it under IFRS 15.56 to 58. Then carry on to step 3 with the constrained figure.
3. IFRS 15.20(a)	Does the scope increase because of added goods or services that are distinct?	The added items, against IFRS 15.27 and 29	Go to step 5. Step 4 is not reached.
4. IFRS 15.20(b)	Does the price increase by an amount reflecting the added items' stand-alone selling prices, adjusted for the circumstances of the particular contract?	The modification consideration against IFRS 15.77 to 79	Go to step 5.
5. IFRS 15.21	Are the remaining goods or services distinct from those already transferred?	Everything not yet transferred, against everything already transferred	All distinct gives 21(a). None distinct gives 21(b). A mixture gives 21(c).

The three reordering errors, and what each one costs

Testing IFRS 15.21 before IFRS 15.20. The entity looks at the remaining goods or services, concludes they are distinct, and applies prospective treatment with a blended rate. But the modification met both IFRS 15.20 conditions, so the correct answer was a separate contract at the addition's own price. The error understates revenue in the periods immediately after the modification if the addition is priced above the original, or overstates it if the addition is priced below. In the units example in unit 10 the difference is CU 1,000 per remaining original unit against CU 950 per added unit, versus a blended figure that is neither. Total revenue over the life of the arrangement is the same; the period profile is not.

Testing distinctness once and reusing the answer. The entity concludes under IFRS 15.20(a) that the added units are distinct, then carries that conclusion into IFRS 15.21 and applies 21(a) automatically. On a units contract that happens to give the right answer. On a construction contract it does not, because IFRS 15.20(a) can fail on the added items while IFRS 15.21's question about the relationship between remaining and already transferred work has its own answer. The two questions coincide often enough that the shortcut survives review, and then fails badly on the contract where it matters most.

Applying the constraint after routing rather than before. The entity routes an unpriced change order to IFRS 15.21(a) using the claimed amount, then applies a haircut to the resulting revenue. IFRS 15.19 requires the constraint to be applied to the change in the transaction price, and IFRS 15.21(a)(ii) then pools "the consideration promised as part of the contract modification", meaning the constrained amount. Constraining after allocation gives a different and unsupportable figure once there is more than one remaining obligation, because the haircut is applied to allocated amounts rather than to the underlying estimate.

Warning. There is no step zero in which the entity asks whether the modification is material. IFRS 15.18 to 21 apply to every approved modification. Materiality operates on the financial statements, not on the routing decision, and a portfolio of individually immaterial change orders routed the wrong way is a well-known route to a material aggregate error. Where an entity applies a practical threshold below which change orders are not individually assessed, the threshold should be supported by an analysis of the aggregate effect, not by an assertion.

A word on the terminology

Search traffic and internal memos routinely use "IFRS 15 retrospective modification" and "IFRS 15 prospective modification" as though the standard used those words. It does not. IFRS 15.21(a) is described as a termination of the existing contract and the creation of a new contract; practitioners call that prospective because nothing already recognised changes. IFRS 15.21(b) is described as accounting for the modification as part of the existing contract with a cumulative catch-up; practitioners call that retrospective because prior revenue is effectively re-based. The shorthand is fine in conversation but it causes two specific problems in practice.

First, "retrospective" implies restatement of comparatives, which IFRS 15.21(b) does not require and IAS 8 would not permit for a change in estimate. The catch-up is a current-period adjustment. Second, "prospective" implies that the modification only affects the future, which is true of revenue already recognised but not of the price applied to undelivered units from the original order. Those units are re-priced. The safest habit is to name the paragraph rather than the label.

Local FAQs

Can we choose between IFRS 15.21(a) and 21(b)?

No. The route follows from whether the remaining goods or services are distinct from those already transferred. That is a factual and analytical conclusion under IFRS 15.27 and IFRS 15.29, not an accounting policy election.

What if we get to IFRS 15.21 and the contract has both satisfied and partially satisfied obligations?

Satisfied obligations are outside the scope of IFRS 15.21 entirely, which addresses the promised goods or services not yet transferred. Partially satisfied non-distinct obligations are the trigger for IFRS 15.21(b). A contract containing both a partially satisfied non-distinct obligation and unsatisfied distinct obligations is the IFRS 15.21(c) hybrid.

Does the assessment change if the modification is one of many?

Each approved modification is assessed on its own facts at its own date, against the position of the contract immediately before it. IFRS 15 contains no aggregation rule for successive modifications. In practice, on a contract with hundreds of variations that all fall to IFRS 15.21(b), the effect is the same as reassessing the whole forecast at each reporting date, which is why contractors run the analysis at contract level rather than variation by variation.

Potential risks

A single distinctness conclusion doing double duty. IFRS 15.20(a) and IFRS 15.21 ask different questions about different populations. One memo cannot answer both unless it addresses both explicitly.
Routing decisions made by systems rather than by people. Where a revenue engine assigns treatment based on order type or contract code, the IFRS 15.20(b) pricing test is not being performed at all.
Materiality applied to routing. Individually small change orders routed by default rather than by test aggregate into a material misstatement on high-volume portfolios.

8. How do modifications interact with a series performance obligation?

A series under IFRS 15.22(b) is a single performance obligation made up of goods or services that are individually distinct. That combination is why modifications to a series go to IFRS 15.21(a) and not to the cumulative catch-up. IFRS 15.21(a) refers expressly to the remaining distinct goods or services in a single performance obligation identified in accordance with paragraph 22(b), so the standard routes the series case for you.

"At contract inception, an entity shall assess the goods or services promised in a contract with a customer and shall identify as a performance obligation each promise to transfer to the customer either: (a) a good or service (or a bundle of goods or services) that is distinct; or (b) a series of distinct goods or services that are substantially the same and that have the same pattern of transfer to the customer (see paragraph 23)."

The critical word is "distinct" in limb (b). A series is not a bundle of non-distinct items. It is a bundle of items that are each distinct but which the standard requires to be accounted for as one obligation because they are substantially the same and transfer in the same pattern. Managed IT services, facilities management, transaction processing, cleaning contracts and repetitive manufacturing all typically sit here.

"A series of distinct goods or services has the same pattern of transfer to the customer if both of the following criteria are met: (a) each distinct good or service in the series that the entity promises to transfer to the customer would meet the criteria in paragraph 35 to be a performance obligation satisfied over time; and (b) in accordance with paragraphs 39 to 40, the same method would be used to measure the entity's progress towards complete satisfaction of the performance obligation to transfer each distinct good or service in the series to the customer."

Note that IFRS 15.23(a) requires each item in the series to qualify for over-time recognition under IFRS 15.35. A repetitive supply of goods that transfers at a point in time cannot be a series, however uniform it is.

Why the series routes to IFRS 15.21(a)

Look again at the wording of IFRS 15.21(a). The consideration to be allocated is allocated "to the remaining performance obligations (or to the remaining distinct goods or services in a single performance obligation identified in accordance with paragraph 22(b))". That parenthesis exists solely to deal with the series. Without it there would be an apparent contradiction: the series is a single performance obligation that is partially satisfied at the modification date, which sounds like the IFRS 15.21(b) trigger, but the remaining goods or services are distinct, which is the IFRS 15.21(a) trigger.

The standard resolves it in favour of IFRS 15.21(a). The IFRS 15.21(b) condition is that the remaining goods or services "are not distinct and, therefore, form part of a single performance obligation that is partially satisfied". Both limbs have to hold. In a series the remaining items are distinct, so IFRS 15.21(b) does not apply, and IFRS 15.21(a) allocates the pooled consideration across the remaining distinct items within the series rather than across separate performance obligations.

The practical result is a blended rate per unit of service for the remaining term. A three-year managed services contract at CU 100,000 a month, modified at month 18 to extend by twelve months at CU 70,000 a month, does not recognise CU 100,000 for months 19 to 36 and CU 70,000 for months 37 to 48. It pools the unrecognised original consideration of 18 months at CU 100,000, which is CU 1,800,000, with the modification consideration of 12 months at CU 70,000, which is CU 840,000, giving CU 2,640,000 over 30 remaining months, or CU 88,000 a month. This is the blend-and-extend arithmetic, and it is the single most commonly misapplied calculation in subscription and outsourcing businesses.

Blend and extend, illustrative example	Incorrect: two rates	Correct: IFRS 15.21(a) blended
Months 19 to 36 (18 months)	CU 100,000 per month	CU 88,000 per month
Months 37 to 48 (12 months)	CU 70,000 per month	CU 88,000 per month
Revenue, months 19 to 36	CU 1,800,000	CU 1,584,000
Revenue, months 37 to 48	CU 840,000	CU 1,056,000
Total over remaining 30 months	CU 2,640,000	CU 2,640,000
Effect	Overstates the next 18 months by CU 216,000	Matches the pooled consideration to the remaining service

Check the arithmetic. Pooled consideration is CU 1,800,000 plus CU 840,000, which is CU 2,640,000. Divided by 30 remaining months that is CU 88,000. Months 19 to 36 at CU 88,000 is CU 1,584,000, and months 37 to 48 at CU 88,000 is CU 1,056,000. The two sum to CU 2,640,000. The incorrect two-rate approach reaches the same total but front-loads CU 216,000 of it, which is 18 months multiplied by the CU 12,000 monthly difference.

Variable consideration in a modified series

Series contracts are usually variable, priced on volume, transactions or usage. Two paragraphs govern how that variability interacts with a modification.

"An entity shall allocate a variable amount (and subsequent changes to that amount) entirely to a performance obligation or to a distinct good or service that forms part of a single performance obligation in accordance with paragraph 22(b) if both of the following criteria are met: (a) the terms of a variable payment relate specifically to the entity's efforts to satisfy the performance obligation or transfer the distinct good or service (or to a specific outcome from satisfying the performance obligation or transferring the distinct good or service); and (b) allocating the variable amount of consideration entirely to the performance obligation or the distinct good or service is consistent with the allocation objective in paragraph 73 when considering all of the performance obligations and payment terms in the contract."

This is the variable consideration allocation exception, and it is what allows a usage-based series to recognise the actual consideration earned in each period rather than an averaged rate. Where IFRS 15.85 is met, the monthly variable fee attaches to that month's distinct service. A modification that changes the future rate then affects only future periods, because the past periods' variable amounts were already allocated to the periods that earned them.

"An entity shall account for a change in the transaction price that arises as a result of a contract modification in accordance with paragraphs 18 to 21. However, for a change in the transaction price that occurs after a contract modification, an entity shall apply paragraphs 87 to 89 to allocate the change in the transaction price in whichever of the following ways is applicable: (a) An entity shall allocate the change in the transaction price to the performance obligations identified in the contract before the modification if, and to the extent that, the change in the transaction price is attributable to an amount of variable consideration promised before the modification and the modification is accounted for in accordance with paragraph 21(a). (b) In all other cases in which the modification was not accounted for as a separate contract in accordance with paragraph 20, an entity shall allocate the change in the transaction price to the performance obligations in the modified contract (ie the performance obligations that were unsatisfied or partially unsatisfied immediately after the modification)."

IFRS 15.90 is the paragraph everyone forgets and it does something subtle. It distinguishes between a change in transaction price that is the modification, which goes through paragraphs 18 to 21, and a change in transaction price that happens after a modification, which goes through the allocation rules in paragraphs 87 to 89. And then it carves out one case: where the later change is attributable to variable consideration that was promised before the modification and the modification was a IFRS 15.21(a) prospective one, the change is allocated back to the pre-modification performance obligations under IFRS 15.90(a).

The practical effect is that a volume rebate or a performance bonus earned on pre-modification activity does not get pooled into the blended forward rate. It is allocated to the obligations it relates to, which may include obligations already satisfied, and IFRS 15.88 then requires amounts allocated to a satisfied performance obligation to be recognised as revenue, or as a reduction of revenue, in the period in which the transaction price changes.

Practitioner note

My view: IFRS 15.90(a) is the paragraph that separates a competent revenue function from a compliant one. Almost every subscription or outsourcing business has both blended-rate modifications and true-up mechanisms on historical volumes. Very few of them have a process that identifies which true-ups relate to pre-modification periods. The consequence is that pre-modification rebates get blended into the forward rate, which spreads over the remaining term an amount that IFRS 15.88 and IFRS 15.90(a) require to hit the current period. It is rarely a huge number in any one quarter, but it is directional, systematic, and it never self-corrects until the contract ends.

Local FAQs

Is a series obligation always modified prospectively?

Where the remaining goods or services in the series are distinct, yes, because IFRS 15.21(b) requires the remaining items not to be distinct. The IFRS 15.21(a) parenthesis referring to paragraph 22(b) exists specifically to make this work. A modification that changes the nature of the service so that the remaining items are no longer substantially the same may break the series, which is a separate question about IFRS 15.22(b) and IFRS 15.23.

Does extending a contract term always create a modification?

Only if the extension changes enforceable rights and obligations. Where the original contract contained an enforceable renewal option exercisable by the customer, exercising it may not be a modification at all, and the option may have been a material right accounted for under IFRS 15.B39 to B43 from inception. Where the extension is negotiated afresh, it is a modification under IFRS 15.18.

How does a price change part way through a usage-based series work?

If IFRS 15.85 is met and the variable amounts are allocated to the distinct periods that earn them, a modification to future rates affects only future periods. If IFRS 15.85 is not met, the variable consideration attaches to the series as a whole and the blended-rate mechanics of IFRS 15.21(a) apply to the estimated total.

Potential risks

Applying the two-rate approach to a blend and extend. The most frequent and most quantifiable error in subscription revenue. It front-loads revenue into the pre-extension period.
Treating a series as one non-distinct obligation. A series is composed of distinct items. Routing it to IFRS 15.21(b) and computing a catch-up applies the wrong paragraph and creates a revenue adjustment that should not exist.
Blending pre-modification true-ups into the forward rate. IFRS 15.90(a) requires changes attributable to variable consideration promised before a IFRS 15.21(a) modification to be allocated to the pre-modification obligations.
Ignoring the effect on the remaining performance obligation disclosure. IFRS 15.120 requires disclosure of the aggregate transaction price allocated to unsatisfied obligations. A blended rate changes that figure and its expected timing.

What regulators look for on modifications

Modifications rarely get challenged on the arithmetic. They get challenged on disclosure, because the routing decision is a judgement that changes the amount and timing of revenue, and IFRS 15.123 requires that judgement to be explained rather than simply applied.

An entity shall disclose the judgements, and changes in the judgements, made in applying this Standard that significantly affect the determination of the amount and timing of revenue from contracts with customers.

A modification routed under IFRS 15.21(b) puts a cumulative catch-up through a single line of revenue. On a large contract that catch-up can be the difference between a growing order book and a profit warning, and nothing on the face of the statements tells a user it happened. That is precisely the kind of judgement paragraph 123 is aimed at, and it is the one most often left out of a revenue policy note.

UK FRC, 2019 thematic review: judgements applied but not shown

The FRC's thematic review of first-year IFRS 15 disclosures found that "one company disclosed that judgement was applied in determining whether revenue was recognised over time or at a point in time but did not detail its evaluation of when the customer obtained control." The same criticism transfers directly to modifications: stating that the group accounts for modifications in accordance with IFRS 15 discloses nothing, because every route in paragraphs 20 and 21 is in accordance with IFRS 15.

The disclosure that carries information is the one that says which route was applied, to what value of modifications, and what the effect on revenue was. Very few policy notes do that.

Financial Reporting Council, IFRS 15 Revenue from Contracts with Customers: Disclosures in the First Year of Application, thematic review, 2019.

What an audit file needs

Three things, and files routinely have only the first. The modification agreement itself, with the date the parties approved it. The distinctness analysis for the remaining goods or services, because that is the fork between IFRS 15.21(a) and 21(b) and it cannot be inferred from the contract value. And the recomputation, showing the unrecognised transaction price carried forward on a prospective route, or the remeasured progress and the catch-up on a continuation route.

My view: the weakest point in most contractor files is not the modification accounting, it is the population. Change orders are administered by operations, not finance, and a modification that never reaches the finance team is not accounted for at all. Testing completeness of the modification population is usually more productive than retesting the ones already booked.

What goes wrong most often

Five patterns cover most of what gets challenged: the routing tests applied out of order, every change order defaulted to a separate contract, prospective treatment forced onto a single non-distinct obligation, a price concession mislabelled, and the catch-up simply not computed.

The tests are applied out of order. IFRS 15.20 is a gate with two conditions, and only if both fail does the analysis move to paragraph 21. Starting at paragraph 21 because the modification "feels like a continuation" skips the standalone selling price test entirely, and a genuinely priced add-on ends up blended into the original contract for no reason.
Every change order treated as a separate contract. Convenient, and wrong wherever the added scope is priced at a discount that does not reflect standalone selling price adjusted for the circumstances of the contract. IFRS 15.20(b) is a real test with a real threshold, not a formality.
Prospective treatment applied to a single partially satisfied obligation. IFRS 15.21(a) requires the remaining goods or services to be distinct from those already transferred. On a construction contract with one integrated performance obligation they are not, so the route is IFRS 15.21(b) and there must be a catch-up. Using the prospective route here spreads a loss forward that the standard requires to be recognised now.
A price concession recorded as a modification. IFRS 15.52 makes consideration variable where the amount depends on customary business practice or a valid expectation, and a concession granted to preserve a relationship is often variable consideration that existed from inception rather than a change in scope or price agreed by the parties. Routing it as a modification moves the effect into the wrong period and bypasses the constraint.
Capitalised contract costs left untouched. A modification that extends or shortens the contract changes the amortisation period under IFRS 15.99 and can trigger the impairment test in IFRS 15.101 to 104. The revenue entry gets made and the cost asset is forgotten.

Frequently asked questions

What is a contract modification under IFRS 15?

IFRS 15.18 defines a contract modification as a change in the scope or price, or both, of a contract that is approved by the parties to the contract. Approval can be in writing, by oral agreement or implied by customary business practices. A modification exists only once it creates new or changes existing enforceable rights and obligations. Until the parties approve it, IFRS 15.18 requires the entity to keep applying the standard to the existing unmodified contract.

When is an IFRS 15 contract modification treated as a separate contract?

Only when both conditions in IFRS 15.20 are met. The scope must increase because of the addition of promised goods or services that are distinct under IFRS 15.26 to 30, and the price must increase by an amount of consideration that reflects the entity's stand-alone selling prices of those additional goods or services, with any appropriate adjustments to reflect the circumstances of the particular contract. If either condition fails, IFRS 15.21 applies instead and the original contract is affected.

What is the difference between prospective and retrospective treatment of an IFRS 15 contract modification?

IFRS 15 does not use the word retrospective. What practitioners call an IFRS 15 retrospective modification is the cumulative catch-up in IFRS 15.21(b), which adjusts revenue already recognised on a single partially satisfied performance obligation at the date of modification. An IFRS 15 prospective modification is IFRS 15.21(a), where the existing contract is treated as terminated and a new contract created, revenue already recognised is untouched, and the remaining consideration is spread over the remaining obligations.

How do you calculate the blended price under an IFRS 15 prospective modification?

Under IFRS 15.21(a) the consideration to allocate to the remaining performance obligations is the sum of the consideration promised by the customer that was included in the transaction price and had not been recognised as revenue, plus the consideration promised as part of the modification. Divide that total by the remaining units or allocate it across the remaining obligations on relative stand-alone selling prices under IFRS 15.74. The result is a single blended rate applied to every remaining unit, whether it came from the original order or the modification.

When does a modification require a cumulative catch-up adjustment?

IFRS 15.21(b) applies when the remaining goods or services are not distinct and therefore form part of a single performance obligation that is partially satisfied at the date of the modification. The effect of the modification on the transaction price and on the measure of progress is recognised as an adjustment to revenue at the date of the modification, either as an increase or a reduction. This is the normal outcome for construction and other integrated contracts that form one performance obligation under IFRS 15.29.

How do you account for an unapproved change order under IFRS 15?

It depends what is unapproved. If nothing has been approved, IFRS 15.18 says keep applying the standard to the existing contract. If the parties have approved a change in scope but have not yet determined the corresponding change in price, IFRS 15.19 requires the entity to estimate the change to the transaction price using the variable consideration guidance in IFRS 15.50 to 54 and to constrain that estimate under IFRS 15.56 to 58. The constrained amount is then routed through IFRS 15.20 or 21 in the normal way.

Is a price concession a contract modification or variable consideration?

If the customer had a valid expectation at inception that the entity would accept less than the stated price, IFRS 15.52 makes the consideration variable from the outset and the later reduction is a change in estimate, not a modification. If the concession is a genuinely new bargain that changes enforceable rights and obligations, it is a modification under IFRS 15.18. The distinction matters because a change in transaction price on an existing obligation is recognised under IFRS 15.88, while a modification may reprice the remaining obligations under IFRS 15.21(a).

Can a reduction in contract scope be a separate contract under IFRS 15?

No. IFRS 15.20(a) requires the scope of the contract to increase because of the addition of promised goods or services that are distinct. A scope reduction fails that condition by definition, so a partial termination or descope is always routed through IFRS 15.21. Where the remaining goods or services are distinct from those already transferred the treatment is prospective under IFRS 15.21(a), and any termination or cancellation fee that the customer is required to pay forms part of the consideration allocated to the remaining obligations.

What happens to capitalised contract costs when a contract is modified?

A modification changes the amount of consideration the entity expects to receive, which is the numerator in the impairment test in IFRS 15.101. If the modification reduces price or extends the work at lower margin, the carrying amount of an asset recognised under IFRS 15.91 or 95 may exceed the remaining consideration less the directly related costs not yet expensed, and an impairment loss is recognised. IFRS 15.102 requires the consideration to be measured without applying the constraint in IFRS 15.56 to 58, and IFRS 15.103 requires other standards to be applied first.

How do contract modifications affect a series performance obligation?

A series of distinct goods or services that are substantially the same and have the same pattern of transfer is a single performance obligation under IFRS 15.22(b), but the underlying goods or services remain distinct. That means a modification to a series is normally routed to IFRS 15.21(a) and not to the cumulative catch-up, because IFRS 15.21(a) refers expressly to the remaining distinct goods or services in a single performance obligation identified in accordance with paragraph 22(b). The catch-up in IFRS 15.21(b) is reserved for remaining goods or services that are not distinct.

Key takeaways

A modification exists only once the parties have approved a change in scope, price or both (IFRS 15.18). Approval can be oral or implied, so the accounting trigger is not the signature date.
Where scope is approved but price is not, IFRS 15.19 requires the change in price to be estimated as variable consideration and constrained. Waiting for the final number understates revenue.
IFRS 15.20 is a two-condition gate. Added distinct goods or services AND a price that reflects standalone selling price adjusted for the circumstances. Both, or the analysis moves on.
The fork inside IFRS 15.21 is distinctness of the REMAINING goods or services. Distinct gives prospective treatment under 21(a) and a blended price going forward. Not distinct gives a cumulative catch-up under 21(b).
A cumulative catch-up lands entirely in the period of modification. On a long contract this is frequently the largest single revenue judgement of the year and it is invisible on the face of the statements.
A commercial concession is often variable consideration under IFRS 15.52 rather than a modification. Check which one it is before routing it, because the period and the constraint both change.

About the Author

Usman is an ACCA-qualified member and an audit and financial reporting professional with a decade of Big 4 experience across Deloitte UK, PwC and BDO, currently an Assistant Manager in Deloitte UK's AI-enabled audit practice. He leads statutory and group audit engagements for multinational clients, with a portfolio in the £20m to £30m fee range and teams of 15 to 25 people across multiple jurisdictions. His technical work concentrates on the judgemental end of the accounting and audit standards. Sector exposure spans banking and financial services, automotive, technology, media and telecom, pharmaceuticals and healthcare, and private equity. Alongside audit delivery he advises CFOs and audit committees on adoption and disclosure decisions, and supports audit partners in forming audit opinions. He has coached more than 150 audit professionals to date, and delivers technical training on accounting and audit standards as well as on new AI tools. He also serves as an AI accelerator at Deloitte, testing new audit technology on live engagements, and built the AI platform behind this site. He writes here on the technical judgements that do not have a straightforward answer in the standards, adding an expert view formed in Big 4 practice.

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UQ Consulting is an independent technical reference for accounting and audit practitioners, covering IFRS, UK GAAP and US GAAP. Every technical assertion on this site carries a paragraph reference to the standard, and only currently effective guidance is presented as the accounting treatment; superseded standards appear as history or comparison only.

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IFRS 15 Contract Modifications: Separate Contract, Prospective or Cumulative Catch-Up

Executive summary

Background

1. What counts as a contract modification under IFRS 15?

The four possible outcomes

Practitioner note

Local FAQs

Potential risks

2. What happens when the scope is approved but the price is not?

Stage one: estimating the price change

Why claims are the hardest case

Balfour Beatty plc

Practitioner note

Local FAQs

Potential risks

3. Route 1: when is an IFRS 15 contract modification a separate contract?

Condition (a): the addition has to be distinct

Condition (b): the price has to reflect adjusted stand-alone selling price

Practitioner note

What separate-contract treatment actually does

Local FAQs

Potential risks

4. Route 2a: how does an IFRS 15 prospective modification work?

The distinctness test in IFRS 15.21 is a different test

The blended rate, and why it looks wrong

Where the remaining obligations are not all the same

Practitioner note

Local FAQs

Potential risks

5. Route 2b: when does an IFRS 15 modification require a cumulative catch-up?

The mechanics, step by step

Why this route is where the money is

Rolls-Royce Holdings plc

BAE Systems plc

Local FAQs

Potential risks

6. Route 2c: how does the hybrid in IFRS 15.21(c) work?

When it actually arises

How to split it defensibly

Practitioner note

Local FAQs

Potential risks

7. Why does the order of the tests decide the answer?

The five questions, in the only order that works

The three reordering errors, and what each one costs

A word on the terminology

Local FAQs

Potential risks

8. How do modifications interact with a series performance obligation?

Why the series routes to IFRS 15.21(a)

Variable consideration in a modified series

Practitioner note

Local FAQs

Potential risks

What regulators look for on modifications

UK FRC, 2019 thematic review: judgements applied but not shown

What an audit file needs

What goes wrong most often

Frequently asked questions

Key takeaways

Related reading in this cluster

About the Author

About UQ Consulting