Every three months, the Canada Revenue Agency (CRA) reviews the interest rate which is charged on amounts due, as well as on amounts they will refund back to you. If you are in arrears with personal taxes, the CRA will currently charge you 5% interest on this amount.
If there is a personal refund which is owed to you, the CRA will refund you interest at the rate of 3%.
The interest will be calculated from the latest of the following three dates: May 31; the day after you have overpaid your taxes owing for the year; or the 31st day after you file your tax return.