Canadian Mortgage Prepayment Savings Calculator
See how much interest and time a monthly prepayment saves — checked against your lender's annual prepayment privilege on your original mortgage amount.
Typically 10-20% of your original mortgage amount, per calendar year — check your specific mortgage agreement.
Your Prepayment Savings
Interest Saved
$57,148
Time Saved
5 years, 1 month
What Is the Canadian Mortgage Prepayment Savings Calculator?
Prepaying a Canadian mortgage — putting extra money toward the principal each month — reduces total interest and shortens your amortization, just like anywhere else. But Canadian lenders structure their prepayment privileges differently from other countries: most allow an annual lump-sum prepayment of 10-20% of your original mortgage principal (not your current outstanding balance), on a use-it-or-lose-it calendar-year basis. This calculator shows the real interest and time saved from a monthly prepayment, checked against your specific lender's privilege.
This also uses Canada's legally required semi-annual compounding convention for mortgage payments — the same formula verified in the Mortgage Stress Test Calculator — rather than the monthly-compounding approach used for mortgages in other countries.
Canadian Mortgage Prepayment Savings Calculator Formula
Effective Monthly Rate = (1 + Annual Rate ÷ 2)^(1/6) − 1
Annual Prepayment Allowance = Original Mortgage Amount × Privilege %
How Is the Canadian Mortgage Prepayment Savings Calculator Calculated?
The standard monthly payment uses Canada's semi-annual compounding formula applied to your current outstanding balance, rate, and remaining amortization. This calculator then simulates the mortgage month by month: each month, interest accrues on the remaining balance at the effective monthly rate, then the standard payment plus your prepayment is applied, with the excess above interest reducing the principal faster than the standard schedule alone.
Unlike UK mortgages, where the overpayment allowance is typically based on the current outstanding balance and recalculates each year, most Canadian lenders base the annual lump-sum privilege on your original mortgage principal at the start of your current term — meaning your maximum annual prepayment allowance generally stays constant rather than shrinking as your balance decreases.
Canadian Mortgage Prepayment Savings Calculator Example
A $400,000 original mortgage with a $380,000 current balance at 4.5% with 25 years remaining, prepaying $300/month: saves about $57,148 in interest and pays off the mortgage 5 years, 1 month early. At$3,600/year, this stays well within a typical 15% ($60,000) annual privilege.
A $300,000 original mortgage with a $280,000 balance at 5% with 20 years remaining, prepaying $500/month: saves about $54,855 in interest and 6 years, 2 months off the term.
A smaller $100,000 original mortgage with a $90,000 balance at 4.5% with 15 years remaining, aggressively prepaying $1,500/month: saves about $25,728 in interest and over 11 years off the term — but at $18,000/year, this exceeds a typical 10% ($10,000) privilege, which could trigger a prepayment charge on the excess.
How to Use the Canadian Mortgage Prepayment Savings Calculator
Step 1
Enter your original mortgage amount and current outstanding balance.
Step 2
Enter your interest rate and remaining amortization.
Step 3
Enter the monthly prepayment you're considering.
Step 4
Enter your lender's specific annual prepayment privilege percentage, and check the warning if it appears.
Benefits
- Uses Canada's legally required semi-annual compounding formula, not a simplified monthly-compounding shortcut.
- Checks your prepayment against the original-principal-based privilege convention Canadian lenders actually use.
- Shows both interest saved and time saved side by side.
- Works for any Canadian lender once you enter their specific privilege percentage.
- Free, instant, and runs entirely in your browser.
Common Canadian Mortgage Prepayment Savings Calculator Scenarios
Scenario 1
Deciding how much to prepay each month without triggering a prepayment charge.
Scenario 2
Comparing different prepayment amounts to find the best balance of savings and affordability.
Scenario 3
Understanding how much faster a mortgage could be paid off with a modest monthly prepayment.
Scenario 4
Checking whether a lump sum from a bonus or tax refund fits within your annual privilege.
Scenario 5
Planning mortgage prepayments around your specific lender's privilege terms.
Understanding Your Result
The interest saved reflects real money that's simply never charged, since a lower balance accrues less interest going forward — this compounds meaningfully over a mortgage's full term. The time saved is how much sooner the mortgage would be fully paid off at the same prepayment level, assuming it continues consistently.
If your prepayment plan exceeds your lender's allowance, the portion above it may trigger a prepayment charge — the specific formula for this charge (often the greater of three months' interest or an interest rate differential calculation) varies significantly by lender, so check your specific mortgage agreement or ask your lender directly before prepaying above your privilege.
Tips
- Since most Canadian lenders base the privilege on your original mortgage amount (not your shrinking balance), your maximum annual prepayment allowance typically doesn't decrease over time — unlike some other countries' conventions.
- The privilege is almost always use-it-or-lose-it on a calendar-year basis — unused prepayment room from one year doesn't carry forward to the next.
- Some lenders let you make both a lump-sum prepayment AND increase your regular payment amount, each with its own separate percentage limit — check whether your lender offers both privileges.
- A prepayment charge, if triggered, is often calculated as the greater of three months' interest or an interest rate differential (IRD) — for a fixed-rate mortgage well below current rates, the IRD can be substantial, so always confirm before prepaying above your privilege.
- Consider whether your mortgage rate is higher than what you could reliably earn elsewhere after tax before assuming prepayment is always the best use of spare money.
Common Mistakes
- Confusing the Canadian privilege convention (based on original principal) with the UK-style convention (based on current outstanding balance), leading to an incorrect allowance calculation.
- Prepaying above the allowance without checking your specific lender's terms, risking an unexpected prepayment charge.
- Assuming unused prepayment privilege carries forward to the next calendar year, when it's almost always use-it-or-lose-it.
- Not checking whether your lender offers both a lump-sum privilege and a separate payment-increase privilege, potentially under-using available prepayment room.
- Assuming prepayment always beats other uses of spare money, without comparing your mortgage rate to what you could earn saving or investing instead.
Frequently Asked Questions
How is the Canadian prepayment privilege different from other countries?
Most Canadian lenders calculate the annual privilege as a percentage of your original mortgage principal (typically 10-20%), which stays roughly constant over your mortgage term — some other countries base the allowance on your current outstanding balance instead, which shrinks over time.
What happens if I prepay more than my privilege allows?
The excess may trigger a prepayment charge, commonly calculated as the greater of three months' interest or an interest rate differential (IRD) calculation — the specific formula and amount vary significantly by lender, so always confirm before prepaying above your privilege.
Does my unused prepayment allowance carry over to next year?
No — almost all Canadian lenders treat the annual privilege as use-it-or-lose-it on a calendar-year basis, so unused room from one year is simply lost when the year ends.
Can I both make a lump-sum prepayment and increase my regular payment?
Many lenders offer both privileges separately, each with its own percentage limit — check your specific mortgage agreement, since not every lender offers both, and the limits can differ between them.
Why does Canada use semi-annual compounding for mortgages?
It's a federal legal requirement under the Interest Act and Bank Act for fixed-rate residential mortgages, and it actually works slightly in the borrower's favour compared to more frequent compounding conventions used elsewhere.
What is an interest rate differential (IRD) charge?
A common Canadian prepayment charge calculation that compares your mortgage's rate to the current rate for a similar remaining term — if your rate is well above current rates, the IRD charge can be substantial, and it's often the larger of the two charge options lenders use.
Does the prepayment privilege apply to variable-rate mortgages too?
Prepayment privileges generally apply to both fixed and variable-rate mortgages, though prepayment charges for variable-rate mortgages are typically calculated differently (often just three months' interest, without an IRD component) — check your specific mortgage type and lender.
Is prepaying always the best use of extra money?
It depends on your mortgage rate compared to what you could earn from savings or investments after tax, your emergency fund situation, and any higher-interest debt you might have instead — prepayment is most clearly beneficial when your mortgage rate is relatively high.
Does prepaying reduce my monthly payment or shorten my amortization?
This depends on your lender's default setting — some automatically reduce future monthly payments, while others keep the payment the same and shorten the amortization instead. This calculator assumes the amortization-shortening approach, which usually saves more interest overall.
Does this calculator account for mortgage default insurance (like CMHC)?
No — this calculator focuses purely on interest savings and payoff timing from prepayment. See the CMHC Insurance Cost Calculator in this category for mortgage default insurance specifically.
How do I find my specific lender's prepayment privilege percentage?
Check your original mortgage agreement or commitment letter, or ask your lender directly — the figure is typically stated clearly as an annual lump-sum percentage and, separately, a payment-increase percentage.
Can I share this prepayment result as an image?
Yes — tap Share and, on supported devices, your result is shared as a branded image card, not just a text link.
References
Important Information
This calculator provides estimates for informational purposes only and is not financial or mortgage advice. Uses Canada's legally required semi-annual compounding formula for fixed-rate mortgage payments; prepayment privilege percentages and charge calculations vary significantly by lender and are not universal figures. Confirm your specific mortgage's prepayment terms and any applicable charges with your lender before making large prepayments.
Last updated: August 2026