Yes, you should report the March 2021 payment on line 10400 of your tax return as a foreign income. It would not be considered a late payment.
As per our TurboTax article: Do You Need to Declare Income Earned From Sources Beyond Canada?
All income that you have earned from foreign and domestic sources must be declared on your personal tax return. Depending on the type of income such as capital gains, investment, or rental property you need to report it the same manner as you would if it was sourced from within Canada.
If the amounts are in a foreign currency, these must be converted to Canadian dollars. Use the Bank of Canada exchange rate that was in effect on the day when you received the income. If it was received a number of times during the year, use the average annual foreign exchange rate to convert into Canadian dollars.
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