Exchange rates for tax

Which exchange rate should you use for your return

When you're converting income, expenses or gains for your tax return, the "exchange rate for tax purposes" is the one your tax authority will actually recognize. Some countries specify an official rate or method in their tax code, so check what applies before you start working with figures.

Every kind of amount might follow its own rule. Salary coming in dollars, a capital gain on crypto sold for yen, or a foreign checking account balance each might need a different method depending on your country’s tax law.

How rate methods work and when they're allowed

Tax rules usually allow one of a few methods:

• Transaction-date rate: Use the rate from the day the money actually arrived, was paid, or a sale happened. This calls for a reliable daily source or historical data.
• Official published rate: This could be from a central bank, your country’s tax office, or a specific agency. While some EU countries let you use the European Central Bank reference rate, others publish a different official number or expect something else.
• Average rate: Some people can use a month or year average for routine wages or expenses (not if the law says otherwise). This can be simpler when you have several small payments.

For cryptocurrencies, you usually have to use the value in your home currency at the moment of each transaction. Exchange prices differ, so always record which one you chose for your calculations.

Pay in dollars? Here’s what happens

If you get a salary of 1,000 US dollars on 15 March, working the math with hypothetical rates, the transaction-date rate might convert it to 900 euros, the monthly average could give you 920 euros, and the yearly average might land at 950 euros.

Those three numbers all came from the same event but are the result of different methods. Which one you have to use will depend on the tax rule in your country. The rates in this example are just for illustration.

Keep your method consistent and keep records

After you pick the method required (or allowed) for your situation, use it across the same type of income or expense for that tax year. If you change methods just to get a better tax result, that can trigger questions, sometimes it’s not even permitted by law.

Save details of each conversion: rate, source, and date. If you’re asked, a clear audit trail makes a big difference. When working out gains, check whether currency exchange gains are taxable, and if you need to know what to keep for crypto, see crypto tax records.

Frequently asked questions