Book the rate you could actually get, and keep the working.

An implementation checklist.

1. 1.Make exchangeability a flag on the currency pair, set at the measurement date and per purpose. The whole amendment turns on one yes or no answer that most systems have never been asked to store: at this date, for this purpose, is the currency exchangeable at all? Put that flag on the rate table, with the date and the purpose it was assessed for, so the rest of the model can read it rather than infer it.
2. 2.Hold the estimated rate as its own value, separate from the feed rate. When a currency is not exchangeable, the rate you use is an estimate, and it will often differ from the official screen rate the feed carries. Keeping both, and recording which one the revaluation used, is what lets you show that the estimate, not the untransactable official rate, drove the numbers.
3. 3.Record the method and its inputs next to the rate. The standard gives more than one way to estimate: an observable rate for another purpose, the first rate once exchangeability returns, or a technique that adjusts an observable rate. Whichever you use, capture the starting observable rate, the adjustment, and a short reason it meets the orderly transaction objective, so the estimate is reproducible and not a single unexplained figure.
4. 4.Assess each purpose on its own, because one currency can be exchangeable for one use and not another. A jurisdiction may let you obtain enough of the other currency to settle trade payables while rationing what you can get to repay borrowings or repatriate a net investment. Model the assessment at the purpose level, so a balance settled for one purpose is not swept into an estimate meant for another.
5. 5.Wire the four disclosures to the rate record, not to a year end memo. IAS 21 asks for the nature and financial effects, the rate used, the estimation process, and the risks. If those four fields live on the same record as the rate, the note is generated from the data. If they live in someone memory until March, the disclosure and the number can drift apart.
6. 6.Treat the first application as a one time, dated event. On adoption the affected balances are translated at the estimated rate at the date of initial application, comparatives are not restated, and the effect goes to opening retained earnings or to the translation reserve depending on the balance. Capture the date of initial application and mark the affected balances, so the opening entry can be explained and reproduced later.
7. 7.Keep the exclusion straight: parallel markets are out of the assessment but allowed in the estimate. You may not point at an unofficial market to argue a currency is exchangeable, because that market does not create enforceable rights and obligations. Once you have concluded it is not exchangeable, you may use an observable rate from such a market, adjusted, to estimate. Encoding that as two different fields keeps the assessment honest and the estimate grounded.
8. 8.Prove completeness with a blocked balance query. The one control that matters is a list of every foreign currency balance whose currency is flagged not exchangeable that has no governed estimated rate and no purpose. While that list has entries, the revaluation is running on assumptions. When it is empty, the estimate covers every balance that needs one, and it can run every close rather than once a year.

Failure modes, framed so you can avoid them.

• Letting the feed rate revalue a balance in a currency you cannot actually trade. The default in most systems is to value every open foreign currency balance at the single rate on the feed. For a non exchangeable currency that official rate can be one no one can transact at in size, so the revaluation looks precise and is wrong. The fix is the exchangeable flag that diverts those balances to an estimated rate.
• Storing one rate per currency pair and calling it done. A currency pair can need a feed rate for exchangeable purposes and an estimated rate for a purpose that is not exchangeable, at the same date. A table with room for only one value forces a choice that hides the judgment. The record needs to hold both, and to say which one each balance used.
• Assessing exchangeability once for the whole currency. Exchangeability is judged per purpose, and a currency can be freely obtainable to pay a supplier yet rationed for a net investment. A single blanket conclusion for the currency either overstates or understates the balances affected. The assessment belongs at the purpose level, even though that is more work.
• Recording an estimated rate with no method behind it. A lone number in a rate field, with nothing to say how it was derived, cannot be defended and cannot be reproduced next quarter. The estimation approach, the observable rate it started from, and the adjustment are the audit trail. Without them the estimate is an assertion.
• Using a parallel market rate to claim exchangeability. It is tempting to point at an active unofficial market and conclude the currency is exchangeable after all. The amendment is explicit that markets without enforceable rights and obligations are excluded from that assessment. Only after concluding a currency is not exchangeable may an observable rate from such a market feed the estimate, and even then with adjustment.
• Writing the disclosures separately from the rate. If the note about nature, effect, rate, process and risk is drafted by hand at year end, away from the record that holds the rate, the two can disagree, and the one users read is the note. Sourcing the disclosure from the same record as the number keeps them consistent by construction.
• Restating comparatives on adoption. The transition does not restate prior periods. The affected balances are translated at the estimated rate at the date of initial application, with the effect taken to opening retained earnings or the translation reserve. A team that instinctively restates the comparative year applies the amendment the wrong way and creates a reconciliation that will not close.
• Assuming the classification never changes. A currency can become not exchangeable, and can later become exchangeable again. If the flag is set once and forgotten, a balance keeps getting an estimated rate long after the market reopened, or keeps getting the feed rate after controls tightened. The assessment is a recurring judgment at each measurement date, not a one time label.

What this asks of the data model.

• The unit is the currency pair at a measurement date for a purpose, not just the currency. Exchangeability, and therefore the rate, is judged at that grain. Modelling the rate record at the pair, date and purpose level is what lets a currency be exchangeable for one use and estimated for another on the same day without contradiction.
• The exchangeable flag is a stored decision with a basis, not a derived value. It is a judgment made at each measurement date, so it needs a place to live, an owner, and a reference to the analysis behind it. Deriving it on the fly from a rate feed misses the point, because the feed cannot tell you whether you could actually obtain the currency.
• The estimated rate and the feed rate are two different fields. One is what a market screen shows, the other is what an orderly transaction would use under prevailing conditions. Holding them separately, and recording which one each balance was revalued at, is what turns the estimate from a silent override into an explainable choice.
• The estimation method is data, with inputs. Whether the estimate came from an observable rate for another purpose, the first subsequent rate, or an adjusted observable rate, the approach and its inputs belong on the record. That is what makes the same rate reproducible at the next close and reviewable by an auditor.
• Purpose is a first class attribute of a foreign currency balance. To route a balance to the right assessment, the balance has to know why the currency would be obtained: to settle an individual item, or to realise a net investment. Without purpose on the balance, the per purpose assessment has nothing to attach to.
• The disclosure content is structured, not prose. Nature and effect, the rate used, the estimation process, and the risks are four defined fields. Storing them as data next to the rate lets the note be generated and lets the same facts feed a group wide summary rather than being rewritten per entity.
• The transition is a dated, one time state on the affected balances. The date of initial application, the fact that comparatives are not restated, and where the opening effect landed are attributes worth stamping on the balances involved, so the adoption entry can be reconstructed years later without re deriving it from memory.
• Completeness is a single testable query. Because every non exchangeable balance needs a governed estimated rate and a purpose, the control is one list: balances flagged not exchangeable with a missing rate or purpose. That query is the readiness signal, and it can run at every close rather than once when the statements are due.

The audit evidence to keep.

• The exchangeability assessment for each affected currency pair, showing the measurement date, the purpose, the conclusion, and the basis for it, including why any parallel market was excluded from the assessment.
• The estimated spot rate used for each affected balance, with the feed rate alongside, so a reviewer can see that the estimate rather than the untransactable official rate drove the revaluation.
• The estimation method and its inputs for each estimated rate: the approach chosen, the observable rate it started from, any adjustment, and the reason the result meets the objective of an orderly transaction under prevailing conditions.
• The mapping from each foreign currency balance to a purpose, so the per purpose assessment can be tied to the balances it governed.
• The four IAS 21.57A disclosures for the period, sourced from the rate records, covering the nature and financial effects, the spot rate or rates used, the estimation process, and the risks from the lack of exchangeability.
• The date of initial application record and the opening transition entry, showing the affected balances translated at the estimated rate at that date, that comparatives were not restated, and whether the effect went to opening retained earnings or the translation reserve.
• The history of the exchangeable flag by currency pair and date, showing when a currency was assessed as not exchangeable and when it was reassessed, so a change in classification is evidenced rather than silent.
• The blocked balance report at close, ideally empty, evidencing that every balance in a currency flagged not exchangeable carried a governed estimated rate and a stated purpose before the revaluation was finalised.

Questions worth asking in your own review.

• For each currency our foreign operations use, can we say at this measurement date whether it is exchangeable, and can we point to the basis for that answer?
• Does our rate table hold room for both a feed rate and an estimated rate on the same currency pair and date, or does it force one value?
• Do we assess exchangeability separately by purpose, so a currency can be exchangeable to settle a payable and not to realise a net investment?
• When we estimate a rate, do we record the method and its inputs, or does a single number sit in the field with nothing behind it?
• Are the four disclosures generated from the same records that hold the rate, or drafted by hand at year end?
• Did we apply the transition the way the amendment sets out, translating affected balances at the estimated rate at the date of initial application without restating comparatives?
• Do our foreign currency balances carry a purpose, so the per purpose assessment has something to attach to?
• Could we produce, today, a list of every balance in a non exchangeable currency that has no governed estimated rate or no purpose assigned?

What this adds up to.

The amendment is a good piece of standard setting. It replaces a gap that let two companies in the same position report different numbers with a consistent way to decide whether a currency is exchangeable, what rate to use when it is not, and what to tell the reader. For most reporters it changes nothing, because their currencies are freely exchangeable. For the ones with a foreign operation behind capital controls, it asks for a rate that is an estimate, and an estimate that can be explained.

The build that makes it easy is small and worth having anyway. Put an exchangeability flag on the currency pair, hold the estimated rate as its own value beside the feed rate, record the method and inputs that produced it, and wire the four disclosures to the same record. Do that and the revaluation and the note read from one governed number, the transition entry can be reproduced, and an auditor who asks how a rate was reached gets an answer that does not depend on anyone remembering the meeting.

If there is one place to start, run the blocked balance query against your own foreign currency positions: any balance in a currency you could not actually obtain at the measurement date, sitting on the feed rate with no estimate behind it. For most companies that list is empty, and the amendment is a note to file. For the ones where it is not, that list is the work, and it is worth doing now, while the first statements under the amendment are still being prepared, because the payoff is a rate you can stand behind and a disclosure that writes itself.

Sources.

• IASB, "IASB sets out accounting requirements for when a currency is not exchangeable", 15 August 2023. The Board announcement of Lack of Exchangeability (Amendments to IAS 21). Primary source for the fact that the amendments fill a gap where IAS 21 previously did not say how to determine the exchange rate when a currency is not exchangeable, the 1 January 2025 effective date, and the framing that companies must apply a consistent approach in assessing exchangeability, determining the rate to use, and the disclosures to provide
• IFRS Foundation, IAS 21 The Effects of Changes in Foreign Exchange Rates, standard landing page. Primary reference for the standard the amendments modify, including its scope over foreign currency transactions, translation to a presentation currency, and translation of a foreign operation
• BDO, IFRB 2023/08, "IASB issues amendments to IAS 21 - Lack of Exchangeability", September 2023. Downloaded as a PDF and read directly rather than through a summariser, per the primary source rule. Source for the two step framework, the meaning of exchangeable in IAS 21.8, the assessment at a measurement date and for a specified purpose in IAS 21.8A, the insignificant amount test in IAS 21.8B, ability rather than intention, the exclusion of markets that do not create enforceable rights and obligations, the objective for estimating the spot rate in IAS 21.19A, the two estimation approaches and their factors, the disclosure objective and four disclosure items in IAS 21.57A, and the transition and date of initial application mechanics
• EY, "Amendments to IAS 21: Lack of Exchangeability", IFRS technical resources. A near primary technical summary used to cross check the assessment of exchangeability by purpose, the estimation approaches, and the additional disclosure requirements when an entity estimates a spot rate
• KPMG, "Exchange rates - Lack of exchangeability", 2024. A near primary technical summary used to corroborate the estimation objective of an orderly transaction between market participants under prevailing economic conditions, and the treatment of multiple observable rates
• EFRAG, "Lack of exchangeability - Amendments to IAS 21", concluded project page. Used to confirm the European Union endorsement route and that the amendments carry the same effective date for annual reporting periods beginning on or after 1 January 2025
• The Association of Corporate Treasurers, "IAS 21: what treasurers need to know about forex accounting standard amendments". A practitioner source used for the operating point that accounting systems commonly keep only one spot rate for each currency pair, and that estimating a rate calls for consistent methods and controls that add to preparation time and audit scrutiny

The two step framework, the meaning of exchangeable and its assessment at a measurement date and for a specified purpose, the insignificant amount test, the treatment of ability rather than intention, the exclusion of markets that do not create enforceable rights and obligations, the objective for estimating the spot rate and the two estimation approaches, the four disclosure requirements, and the transition and date of initial application mechanics were read directly from the BDO IFR Bulletin, downloaded as a PDF and read rather than summarised. The effective date and the framing of the change were taken from the IASB announcement and the IAS 21 standard page, and were cross checked against the EY and KPMG technical summaries, the EFRAG endorsement record, and the practitioner note from the Association of Corporate Treasurers, so no fact here rests on a single secondary source alone. No embedded posts from X appear in this article, because no public post on the amendment could be verified as current, relevant and authentic at the time of writing, and an unverified embed is worse than none. Nothing here is accounting, tax or legal advice for a specific company. Whether a currency is exchangeable, and the rate to use when it is not, depend on an entity facts and judgment applied under the standard, and the figures in the model above are placeholders for shape rather than real rates.