Short answer
You do not reopen and refile the original return. You put the correction into a subsequent return, identifying the Member State of consumption, the tax period being corrected and the amount of VAT concerned.
The key rules:
- Mechanism. Article 369g(4) of the VAT Directive requires amendments to be included in a subsequent return. Article 61 of the Implementing Regulation confirms that, for periods from the third return period of 2021 onwards, changes are made "only by adjustments in a subsequent return".
- Window. Three years from the date the original return was due.
- Rate. The rate and rules of the original period, not the period in which you make the correction.
- Exchange rate. The one applying to the original period.
- After you leave the scheme. Corrections arising after your final return are settled directly with the Member State of consumption, not through OSS.
Underlying all of this is Article 90(1), which requires the taxable amount to be reduced on cancellation, refusal, price reduction or non-payment.
Why a refund reduces the tax at all
"In the case of cancellation, refusal or total or partial non-payment, or where the price is reduced after the supply takes place, the taxable amount shall be reduced accordingly under conditions which shall be determined by the Member States." —
Note the closing words. The entitlement is EU-wide, but the conditions are set nationally, and the relevant national rules are those of the Member State of consumption — the country whose VAT you charged, not the country where you file.
Article 90(2) allows Member States to derogate in cases of total or partial non-payment. That matters for bad debts. It does not apply to a straightforward refund of goods returned, which falls squarely in the first limb.
The correction mechanism
Article 369g(4), for the Union scheme:
"Where any amendments to the VAT return are required after its submission, such amendments shall be included in a subsequent return within three years of the date on which the initial return was required to be submitted pursuant to Article 369f. That subsequent VAT return shall identify the relevant Member State of consumption, the tax period and the amount of VAT for which any amendments are required." —
Article 365 makes the same provision for the non-Union scheme, and Article 369t(2) for the import scheme.
The Implementing Regulation is explicit that the two possible approaches are not interchangeable, and that the cutover has passed:
"Changes to the figures contained in a VAT return relating to periods from the third return period in 2021 shall, after the submission of that VAT return, be made only by adjustments in a subsequent return." —
So for any period you are realistically dealing with now, the answer is the subsequent-return route. There is no "amended Q3 return" to file.
What the correction line contains
Three data points, per Article 369g(4): the Member State of consumption, the tax period being corrected, and the VAT amount.
Practical points that follow:
Use the original period's rate. If Ireland's rate changed between the sale and the refund, the correction reverses tax at the rate charged on the original supply. You are undoing a past transaction, not creating a new one.
Use the original period's exchange rate. Article 369h requires the return to be made out in euro, using the exchange rate applying on the last date of the tax period, published by the European Central Bank. A correction to an earlier period uses that earlier period's rate. Applying today's rate introduces a currency difference that will not reconcile.
Corrections can be negative. A return period in which refunds exceed sales for a given Member State produces a negative figure for that state. This is normal. How the resulting credit is settled — offset or repayment — is handled between the Member State of identification and the Member State of consumption; the position is not always symmetrical across states, so expect timing differences rather than instant offset.
Partial refunds are partial corrections. Refunding delivery charges but not the goods, or refunding one line of a multi-line order, corrects only that amount.
Which period does the refund belong to?
This is the question that causes most of the confusion.
The correction is attributed to the tax period of the original supply, because that is the period whose figures were wrong once the price was reduced. It is not reported as a negative sale in the current period.
That is why Article 369g(4) requires you to identify the tax period being amended. A system that simply nets refunds against current-period sales will produce a return that cannot be reconciled to any Member State's records.
Your billing data therefore needs to carry the original supply date and original period on every refund record. Retrofitting that link later, across several years and 27 consumption states, is painful.
Records: the Directive tells you what to keep
Article 63c of the Implementing Regulation specifies what OSS records must contain. Two items are directly about corrections:
"(e) any subsequent increase or reduction of the taxable amount ... (l) any proof of possible returns of goods, including the taxable amount and the VAT rate applied." —
Article 63c(3) requires the information to be recorded so that it can be made available electronically without delay and in respect of each individual good or service supplied. If a request is not answered within 20 days, the Member State of identification issues a reminder and notifies the Member States of consumption.
"Without delay" and "each individual good or service" together rule out a spreadsheet of monthly totals. Keep transaction-level data.
The retention period is ten years: Article 369k(2) for the Union scheme, running from 31 December of the year of the transaction; Article 369 and Article 369x for the non-Union and import schemes.
After you leave the scheme
Article 61a of the Implementing Regulation deals with cessation, exclusion, and change of Member State of identification. The final return and any late previous returns go to the state that was the Member State of identification at the time. Then:
"Any corrections to the final return and previous returns arising after the submission of the final return shall be discharged directly with the tax authorities of the Member State of consumption concerned." —
A business that deregisters from OSS and then processes refunds on pre-exit sales must deal with each consumption state individually. That is a materially heavier process than a correction line in a live return, and it is a good reason not to deregister while a returns window is still open.
The same applies where you change Member State of identification under Article 57f: corrections arising after the final return go direct to the consumption states.
Import scheme specifics
For IOSS, Article 369t(2) mirrors the three-year subsequent-return rule. Article 369s requires monthly returns rather than quarterly.
Article 61b of the Implementing Regulation defines the chargeable event by reference to acceptance of payment: the time the payment confirmation, payment authorisation message or commitment to pay is received, whichever is earliest — regardless of when money actually moves. For a refund correction, that fixes which period the original supply sat in.
Returned imported goods also raise a customs question — whether import duty is repaid, and under what procedure — which is separate from the IOSS VAT correction and follows customs rules.
Operational checklist
- Link every refund record to the original supply's date, period, Member State, rate and exchange rate.
- Correct through a subsequent return, never by refiling the original.
- Identify Member State of consumption, tax period and amount on each correction line.
- Apply the original period's rate and ECB exchange rate.
- Diarise the three-year limit from each period's due date.
- Keep transaction-level records, including proof of returns, for ten years.
- Be able to respond to a records request within 20 days.
- Do not deregister from OSS while corrections on past periods remain likely.
Conclusion
An OSS refund correction is a forward-looking entry about a backward-looking period. You report it in the next return, but you value it using the original period's rate and exchange rate, and you tag it to that period explicitly.
Most failures here are data failures rather than legal ones: refund records that do not carry the original supply's period and rate cannot produce a compliant correction line. Build that link at the point of sale, and the three-year window, the ten-year retention and the 20-day production requirement all become routine.
Sources
This article provides general legal information, not advice for a specific matter. Laws, facts and procedural deadlines may change the result. Follow the linked primary sources and obtain local advice before acting.