The Inland Revenue Authority of Singapore (IRAS) has updated its guidance on foreign currency transactions and foreign exchange gains or losses for GST purposes, providing further clarification on the use of exchange rates, the treatment of different transaction types and the classification of foreign exchange differences. The updated guidance, dated 28 September 2026, is relevant to GST-registered businesses that issue invoices, receive payments or enter into transactions denominated in foreign currencies.
The clarification is particularly important for businesses engaged in international trade, cross-border services and transactions involving overseas customers or suppliers. Businesses should ensure that their accounting systems and GST reporting procedures distinguish between the Singapore dollar value of a taxable supply and any subsequent foreign exchange gains or losses arising from currency movements.
Foreign Currency Transactions: GST Reporting Requirements
Singapore GST is administered and reported in Singapore dollars (SGD). Where a GST-registered business makes a taxable supply denominated in a foreign currency, the relevant amounts must be converted into SGD for GST reporting purposes using an exchange rate permitted under IRAS requirements.
For example, a Singapore business issuing an invoice in US dollars must determine the corresponding SGD value of the taxable supply and the GST amount. The conversion should follow the applicable GST time-of-supply rules and the relevant IRAS requirements for exchange rates. Businesses should not automatically use the exchange rate prevailing on the date of payment if the GST time of supply occurred earlier.
Approved Local and Global Exchange Rate Sources
The updated guidance addresses the exchange rate sources that businesses may use for GST purposes. These include approved local and global exchange rate sources, subject to the conditions specified by IRAS. Businesses should establish an appropriate exchange rate policy that addresses:
- The source of exchange rates used for GST conversion.
- The date on which the relevant exchange rate is determined.
- Consistent application of the selected exchange rate methodology.
- Documentation supporting the rates used in GST computations.
- System controls to prevent unauthorised changes to exchange rate settings.
The exchange rate used for GST purposes may differ from the rate used for accounting purposes, depending on the applicable requirements and accounting policies. Where differences arise, businesses should maintain appropriate reconciliation records.
GST Treatment of Different Transaction Types
Foreign currency transactions may arise in several business situations, each requiring consideration of the applicable GST rules.
| Transaction type | Key GST consideration |
|---|---|
| Local taxable sales invoiced in foreign currency | Determine the SGD value of the supply and output GST using the applicable conversion requirements |
| Zero-rated exports or international services | Apply the relevant zero-rating conditions and maintain supporting evidence |
| Local purchases invoiced in foreign currency | Determine the SGD value of input tax based on valid supporting documents and applicable input tax rules |
| Foreign currency payments received after invoicing | Assess exchange differences separately from the original taxable supply |
| Foreign currency payments to suppliers | Distinguish exchange differences arising on settlement from the GST treatment of the underlying purchase |
The GST treatment depends on the nature of the underlying transaction and should not be determined solely by the currency in which the invoice or payment is denominated. A transaction does not become zero-rated or outside the scope of GST merely because it is invoiced or settled in a foreign currency.
Foreign Exchange Gains and Losses: GST Implications
The updated guidance also addresses the identification and treatment of different types of foreign exchange gains and losses. Foreign exchange differences commonly arise when exchange rates change between the recognition of a transaction and its subsequent settlement or remeasurement.
A. Realised Foreign Exchange Gains and Losses
Realised exchange gains or losses may arise when a foreign currency receivable or payable is settled at an exchange rate different from the rate used when the transaction was initially recorded.
For example, a business may invoice a customer in US dollars and receive payment several weeks later, when the exchange rate has changed. The resulting accounting exchange gain or loss generally represents a currency movement rather than an additional payment for the underlying supply. Businesses should therefore distinguish settlement-related exchange differences from changes to the consideration for the supply.
B. Unrealised Foreign Exchange Gains and Losses
Unrealised exchange gains or losses may arise when foreign currency monetary balances are retranslated at a reporting date.
These amounts generally arise from accounting remeasurement rather than a separate supply of goods or services. Businesses should ensure that accounting retranslation entries do not automatically generate GST adjustments without an appropriate GST basis.
C. Foreign Exchange Transactions as Financial Activities
A distinction must also be made between exchange gains or losses arising incidentally from trade transactions and transactions involving the exchange of currencies as a financial activity.
Currency exchange transactions may fall within the GST rules for financial services, including applicable exemptions. Businesses should assess the nature of the transaction rather than treating all foreign exchange-related amounts in the same manner.
Illustration: Foreign Currency Invoice and Subsequent Settlement
Assume a GST-registered Singapore company issues a standard-rated invoice for USD10,000. For illustration, assume the applicable GST exchange rate at the relevant time of supply is USD1 = SGD1.35.
| Particulars | Amount |
|---|---|
| Invoice value | USD10,000 |
| Applicable exchange rate | 1.35 |
| Taxable value in SGD | S$13,500 |
| GST at 9% | S$1,215 |
| Total invoice value in SGD | S$14,715 |
If the customer subsequently pays when the exchange rate has moved to SGD1.38, an exchange difference may arise in the company’s accounting records. However, the exchange rate movement does not, by itself, require the original output GST to be recalculated.
The original GST amount remains determined by the applicable time-of-supply and foreign currency conversion requirements, unless a separate event requires a GST adjustment. This example assumes that USD10,000 is the GST-exclusive consideration and that the applicable conversion rate is 1.35. It is illustrative and does not prescribe a particular exchange rate source.
Practical Implications
The updated guidance highlights several areas requiring attention from finance and tax teams.
Exchange rate policy
Businesses should confirm that their exchange rate sources and conversion procedures comply with the applicable IRAS requirements.
Accounting and GST reconciliation
Differences between accounting exchange rates and GST conversion rates should be properly reconciled.
System configuration
ERP and accounting systems should distinguish between transaction exchange rates, GST conversion rates and settlement exchange rates.
Foreign exchange classification
Realised and unrealised exchange gains or losses should be separately identifiable where necessary for GST analysis.
Supporting documentation
Businesses should retain relevant invoices, exchange rate records, accounting schedules and supporting documents to substantiate the GST amounts reported.
Recommended Action
GST-registered businesses should consider the following compliance measures:
- Review exchange rate sources: Verify that the exchange rate providers used for GST reporting are permitted under the updated IRAS guidance.
- Check foreign currency invoicing procedures: Ensure that GST amounts are determined and presented in accordance with applicable requirements.
- Review GST time-of-supply controls: Confirm that the correct date and exchange rate are used when converting foreign currency transactions.
- Reconcile exchange differences: Distinguish exchange gains and losses arising from settlement or remeasurement from adjustments to the underlying transaction value.
- Assess financial transactions separately: Determine whether currency exchange activities constitute exempt financial supplies under the applicable GST rules.
- Update accounting procedures: Revise internal policies and system configurations where necessary to reflect the updated guidance.
Conclusion
The updated IRAS guidance reinforces the importance of correctly converting foreign currency transactions into Singapore dollars and distinguishing foreign exchange differences from the GST treatment of the underlying transactions. For GST-registered businesses, the principal compliance considerations are the selection of permitted exchange rate sources, the correct treatment of different transaction types and the appropriate classification of foreign exchange gains or losses.
Businesses with significant foreign currency transactions should review their GST conversion procedures and accounting controls to ensure consistent and accurate reporting.
Technical Notes
This article appropriately distinguishes the original GST liability from subsequent currency movements. The 9% GST calculation is illustrative. Businesses should apply the exchange rate source, conversion method and transaction-specific rules permitted by IRAS rather than assuming that their financial reporting exchange rate is automatically acceptable for GST.
This article provides general technical information and does not constitute specific tax advice. The GST treatment of foreign currency transactions depends on the nature of the transactions, applicable GST legislation and prevailing IRAS guidance.
Source: IRAS, 28 September 2026.