Official Euro Exchange Rates: Key Points for Companies with Foreign Currencies (March 23, 2026)

Key data

Companies that operate with foreign currencies have a specific obligation: to use the official exchange rate published by the Banco de España to value their international transactions for accounting and tax purposes. On March 23, 2026, the Banco de España published the official euro exchange rates established by the European Central Bank, with legal validity pursuant to Article 36 of Ley 46/1998, de 17 de diciembre, sobre la Introducción del Euro.

These rates are not indicative: their publication in the BOE gives them official and binding status for certain legal and accounting obligations. Ignoring them or replacing them with market rates in accounting records or tax returns is a mistake with real consequences.

What does this regulation establish?

The Banco de España Resolution of March 23, 2026 publishes the euro exchange rates against foreign currencies fixed that day by the European Central Bank. This is a daily process responding to an obligation established in Article 36 of Ley 46/1998.

The legal framework is clear: the published rates are considered official exchange rates. This means they are the reference rates for:

• The conversion of foreign currency transactions for accounting purposes, in accordance with the Plan General de Contabilidad.
• The valuation of international transactions declared before the Agencia Tributaria.
• The settlement of contracts denominated in foreign currency when the contract refers to the official rate.
• Any legal obligation requiring conversion to euros using the official rate on the date of the transaction.

The Banco de España acts as the publisher in Spain of the rates set by the ECB, giving them legal validity within the Spanish legal system through their publication in the BOE.

Economic and operational impact

The impact is not abstract. Every company that records an invoice in dollars, pounds, yen or any other currency in its accounts needs a reference exchange rate. If that transaction took place on March 23, 2026, the applicable rate is the one published in this resolution.

The practical consequences of not applying the official rate are:

• Accounting valuation differences that can distort the financial result for the period.
• Tax discrepancies in the declaration of foreign currency transactions before the Agencia Tributaria, with the risk of reassessment.
• Contractual disputes if the foreign currency contract references the official rate and a different one is applied.

For companies with a high volume of international transactions, the difference between the official rate and the intraday market rate may be small in percentage terms, but significant in absolute value when applied to large transactions.

Who is affected?

• Importing companies: that receive invoices in foreign currencies and must record them in euros in their accounts.
• Exporting companies: that issue invoices in foreign currencies and must convert them to euros for tax reporting purposes.
• Companies with contracts in foreign currency: loans, leases, supply or service contracts denominated in foreign currencies.
• Financial professionals and corporate treasurers: who manage foreign currency positions and need the official rate for accounting closings.
• Tax and accounting advisors: who prepare returns or year-end closings involving international transactions for their clients.
• CFOs and financial directors of companies with international activity who oversee the valuation of assets and liabilities in foreign currency.

Practical example

A Spanish company imports machinery from the United States and receives an invoice for 500,000 dollars dated March 23, 2026. To record this transaction in its accounts in euros, it must apply the official euro/dollar exchange rate published by the Banco de España in this resolution, corresponding to that day.

If the company were to use an intraday market exchange rate different from the official one, the amount recorded in euros could differ from the result of applying the official rate. That difference, even if it appears small as a percentage, becomes an accounting and tax discrepancy that the Agencia Tributaria may detect during an audit. The official rate for March 23, 2026 is the one published in the BOE through this resolution: that is the figure that must appear in the accounting entry and in any related tax return for that transaction.

What should companies do now?

1. Identify all foreign currency transactions dated March 23, 2026: invoices issued or received, collections, payments and contracts settled on that date.
2. Apply the official exchange rate published in this resolution to convert those transactions to euros in the accounts, instead of using market rates or estimates.
3. Verify that accounting systems and ERPs are configured to import or record the official ECB exchange rates published daily by the Banco de España.
4. Review foreign currency contracts with settlements or maturities on this date to ensure that the conversion is carried out using the correct official rate.
5. Coordinate with the tax advisor any relevant foreign currency transactions on this date before submitting returns that include those transactions.

Official source

Disclaimer: This article is for informational purposes only and does not constitute legal advice. For specific decisions, please consult a qualified professional. Source: https://www.boe.es/diario_boe/txt.php?id=BOE-A-2026-6866