How Mortgage Amortization Works in Canada (Why Early Payments Are Mostly Interest)
By Jordan Ellis · Published · Reviewed
Quick Answer
Amortization is paying off a mortgage through fixed monthly payments that split between interest and principal. On a $450,000 Canadian mortgage at 5% over 25 years, about 71% of the first $2,618 payment is interest — but the share shifts toward principal every month until the balance hits zero. Canadian fixed rates compound semi-annually by law, which works slightly in your favour.
The basic mechanic
A fixed-rate mortgage has a fixed monthly payment, but what’s inside that payment changes every month. Each month’s interest is charged on the remaining balance:
Monthly interest = remaining balance × effective monthly rate
In Canada, fixed rates compound semi-annually by law, so the effective monthly rate is (1 + annual rate ÷ 2)1/6 − 1. Whatever is left of your payment after interest goes to principal. Since the balance is highest at the start, interest eats most of early payments.
A real Canadian example
A $450,000 mortgage at 5% over 25 years. The monthly payment is $2,618.
| Payment | Interest | Principal | Remaining balance |
|---|---|---|---|
| 1 (month 1) | $1,856 | $762 | $449,238 |
| 60 (year 5) | ~$1,642 | ~$976 | ~$398,265 |
| 180 (year 15) | ~$1,020 | ~$1,598 | ~$247,340 |
| 300 (final) | ~$11 | ~$2,607 | $0 |
Five years in — after more than $157,000 in payments — you’ve reduced the balance by only about $52,000. That’s not a scam; it’s arithmetic. But it explains why understanding amortization matters before you sign.
Why lenders front-load interest (and what it means for you)
Interest is the lender’s fee for the money you’re still using. Since you owe the most at the beginning, the fee is largest then. The practical consequences:
- Selling or breaking the mortgage early is expensive. In the first 5 years, most of what you paid bought you little equity — and breaking a fixed term can add an IRD penalty on top.
- Prepayments punch hardest early. An extra dollar of principal in year 1 saves interest for the remaining ~24 years; the same dollar in year 20 saves almost nothing.
- Shorter amortizations are dramatically cheaper. A 20-year version of the mortgage above costs roughly $260,000 in interest versus $335,000 for 25 years — because the balance falls fast from day one.
How to use this to your advantage
- Use your prepayment privileges. Most Canadian lenders allow annual lump sums of 10–20% of the original principal plus payment increases. Paying $2,800 instead of $2,618 on the example mortgage saves roughly $49,000 in interest and cuts about 3 years.
- Accelerated biweekly payments. Paying half the monthly amount every two weeks creates 13 monthly payments a year instead of 12 — shaving about 3 years off a 25-year amortization on its own.
- Renew into lower rates without dropping your payment. At renewal, keep paying the old amount; the difference goes straight to principal.
Run your own numbers with our mortgage calculator — it shows the full amortization schedule with semi-annual compounding, so you can see exactly where every dollar goes.
The bottom line
Amortization isn’t a trick, but it rewards people who understand it. Fixed payments are simple on the surface; the interest-versus-principal split underneath is where the real money moves. Attack the principal early, and the schedule bends in your favour.
Official sources
Rules and dollar limits change. Confirm current amounts with the official pages below before you act · Last reviewed .
- Mortgage prepayment penalties (Financial Consumer Agency of Canada)