Guide · Canada
How Canadian Mortgage Interest Compounding Works
Last updated 2026-06-27 · Published 2026-06-27
Understand the unique compounding rules for Canadian mortgages. Learn why fixed and variable rates compound differently, and how it impacts your payments.
Fixed-Rate Mortgages: Semi-Annual Compounding
In Canada, the Interest Act dictates that interest on fixed-rate mortgages must be compounded semi-annually (twice per year), not monthly.
This is a major difference from the US, where mortgages compound monthly. Semi-annual compounding is actually a benefit to borrowers: it means the effective rate of interest is slightly lower than if it compounded monthly.
Variable-Rate Mortgages: Monthly Compounding
Unlike fixed rates, variable-rate mortgages in Canada are typically compounded monthly. This means interest is calculated and added to the principal balance every month.
Because of this difference, when comparing a fixed rate and a variable rate that look identical on paper, the fixed-rate mortgage will accrue slightly less interest over time due to the compounding frequency.
How Compounding Affects Your Payments
While compounding math is complex, mortgage calculators handle this behind the scenes. For a Canadian fixed rate, the calculator first determines the 'effective monthly rate' by converting the semi-annually compounded annual rate.
This ensures that your payments match the legal requirements of the Canadian Interest Act. Knowing how compounding works helps you compare loan offers accurately.
Try the numbers yourself
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Go to calculator →Frequently asked questions
Why do Canadian fixed mortgages compound semi-annually?
It is a historical legal requirement under the Canadian Interest Act designed to protect consumers by capping how frequently lenders can compound interest on residential real estate loans.
Does compounding frequency change my monthly payment amount?
Yes, but the difference is small. A $400,000 loan at 5% interest compounded semi-annually has a monthly payment that is about $2 to $3 cheaper than the same loan compounding monthly.
Educational content only—not mortgage, tax, or legal advice. Confirm any decision with a licensed professional in your jurisdiction.