Income (wages, interest, dividends, pensions): the IRS yearly average. Sales of investments: the rate on the day you bought and the day you sold. Account values on the FBAR and Form 8938: the US Treasury rate for December 31.
The rates are Canadian dollars per US dollar, so you divide the Canadian amount by the rate.
IRS yearly average rates
The IRS says it has no official exchange rate and generally accepts any posted rate you use consistently. Its published yearly averages are the usual choice for income received through the year:
Example: T4 box 14 of CA$84,500 in 2025 is $84,500 ÷ 1.398 = $60,443.49 on your US return.
Canadian income tax claimed for the foreign tax credit on the accrual basis also uses the yearly average for the year it relates to, as long as it is paid within two years.
Daily rates for sales
When you sell shares or fund units, your US gain is the US dollar value of what you received minus the US dollar value of what you paid. Convert the cost at the rate on the purchase date and the proceeds at the rate on the sale date. A sale that lost money in Canadian dollars can be a gain in US dollars, and the other way around.
Treasury December 31 rates for account reports
The FBAR instructions require the Treasury's Reporting Rate of Exchange for the last day of the calendar year, and Form 8938 uses the same rate for year-end values.