Exchange rates on customs declarations vs. exchange rates on invoices: two rates, two purposes

In September 2026, the Department of Customs and the Department of Taxation each gave their views on a common concern of enterprises with foreign-currency transactions: which exchange rate should be shown on the invoice, and must it match the customs declaration? According to the two official letters, the customs declaration uses the tax calculation exchange rate under customs law, whereas the invoice uses the actual transaction exchange rate under accounting law. A difference in the VND-converted amounts between documents is not a difference in the value of goods, and enterprises are not required to amend the customs declaration merely to make the VND amounts match.

1. Official Letter No. 21591/CHQ-NVTHQ: the exchange rate on customs declarations

The tax calculation exchange rate is determined under Clause 5, Article 21 of Decree No. 08/2015/ND-CP (as amended and supplemented by Clause 9, Article 1 of Decree No. 167/2025/ND-CP):

• It is the buying rate by bank transfer of the Head Office of the Joint Stock Commercial Bank for Foreign Trade of Vietnam (Vietcombank) at the end of the Thursday of the immediately preceding week. If that Thursday is a public holiday or a day off, the end-of-day rate of the working day immediately before it is used. This rate applies to customs declarations registered during the week.
• For foreign currencies whose rates are not announced by this bank, the cross rate announced by the State Bank of Vietnam is used. Where no cross rate is available, the State Bank of Vietnam determines and announces the rate at the request of the Ministry of Finance.

Enterprises declare and determine the customs value using the exchange rate applicable at the time of registering the customs declaration, for the purpose of calculating export duty and import duty.

Two conclusions of the Department of Customs:

• Where the transaction value in foreign currency is consistent but the VND-converted amount on the customs declaration differs from the converted amount on other documents, because the enterprise uses different exchange rates for different purposes, the difference in VND amounts is not regarded as a difference in the value of goods.
• Enterprises are not required to amend the customs declaration solely to make the VND-converted amounts on the documents identical, provided that the contents relating to the nature of the transaction and the value of goods in foreign currency are consistent with the actual dossiers and documents.

2. Official Letter No. 6810/CT-QLNT: the exchange rate on invoices

The Department of Taxation relies on Point c.1, Clause 8 of the Appendix to Decree No. 254/2026/ND-CP and on Clause 1 and Point a, Clause 5, Article 26 of the Law on Tax Administration No. 108/2025/QH15. Under Article 26, e-invoices must contain all contents required by tax law and accounting law, and must fully and truthfully reflect the economic transactions arising. The official letter distinguishes two cases:

• Cases permitted to declare taxes and other revenues in foreign currency (Clause 1, Article 14 of Decree No. 252/2026/ND-CP): the currency for declaring and paying taxes and other revenues, and the exchange rate for converting declared tax, follow Article 14 of Decree No. 252/2026/ND-CP.
• Economic and financial transactions arising in foreign currency in accordance with foreign exchange law: the seller shows on the invoice the exchange rate between the foreign currency and Vietnamese dong in accordance with Point c.1, Clause 8 of the Appendix to Decree No. 254/2026/ND-CP; this rate is the actual transaction exchange rate determined in accordance with accounting law.

3. Revenue for corporate income tax (CIT) purposes (Section 3 of Official Letter No. 21591/CHQ-NVTHQ)

Revenue is determined under Article 8 of the Law on Corporate Income Tax No. 67/2025/QH15 and Article 8 of Decree No. 320/2025/ND-CP. It comprises all proceeds from sales of goods, processing and provision of services, and other amounts to which the enterprise is entitled, regardless of whether payment has been received. For sales of goods, the time of revenue determination is the time of transfer of ownership of, or the right to use, the goods to the buyer (Clause 2, Article 8 of Decree No. 320/2025/ND-CP).

💡 Recommendations for enterprises

• Review foreign-currency invoices issued since 1 July 2026. If the customs exchange rate has been used on invoices, enterprises should reassess this and consult their directly managing tax authority.
• Update internal procedures and invoicing software to separate the source of exchange rates used for invoices and accounting books from the exchange rate used for customs declarations.
• Retain complete records demonstrating that the foreign-currency value is consistent across the contract, the invoice and the customs declaration, so as to be ready to explain any difference in VND-converted amounts.
• Note that the two official letters are guidance documents, not legal normative documents; enterprises should continue to monitor further guidance from the Ministry of Finance.

This newsletter is prepared by Crowe Vietnam for general information purposes only and does not constitute advice for any specific case. Enterprises should refer to the original legal instruments and consult professional advisors before applying the above to their particular circumstances.