What exchange rate should be used when filing my return?

All income and expenses on your tax return must be reported in U.S. dollars. In general, you can use the exchange rate on the day a payment or expense was received or paid, or an average annual exchange rate. To use the average annual exchange rate, your income and expenses need to be earned or paid evenly throughout the year. The IRS average annual exchange rates for most currencies are posted here:

https://www.irs.gov/individuals/international-taxpayers/yearly-average-currency-exchange-rates