Breaking a fixed-rate mortgage in Canada before the term ends triggers a prepayment penalty — typically the greater of 3 months' interest or the Interest Rate Differential (IRD). This calculator estimates both figures so you can understand your potential cost before making any decisions.
IRD Penalty Estimator
How IRD Is Calculated in Canada
The Interest Rate Differential (IRD) penalty is designed to compensate your lender for the interest income they lose when you break your mortgage early. The formula:
IRD = (Your Contract Rate − Lender's Current Rate) × Outstanding Balance × (Months Remaining ÷ 12)
The "lender's current rate" is the critical variable. Banks use their posted rate for the term closest to your remaining term, minus any discount you received. This inflates the penalty significantly compared to monoline lenders, which use their actual current market rate.
Bank IRD vs. Monoline IRD: A Critical Difference
| Lender Type | Comparison Rate Used | Typical Penalty Impact |
|---|---|---|
| Big 6 Banks | Posted rate minus your original discount | Very high — often $15,000–$40,000+ |
| Monoline Lenders | Current market rate for remaining term | Lower — often $5,000–$15,000 |
| Credit Unions | Varies by institution | Moderate — ask explicitly |
Example: You got your mortgage at a 1.5% discount off the bank's 5-year posted rate of 6.39% (so your contract rate was 4.89%). Now there are 2.5 years left and the bank's 2-year posted rate is 5.49%. The comparison rate becomes 5.49% minus 1.5% = 3.99%. Your IRD = (4.89% − 3.99%) × balance × 2.5 years. The posted-rate methodology inflates the penalty by embedding your original discount into the formula.
3-Month Interest Penalty
The simpler of the two calculations: Outstanding Balance × Annual Rate ÷ 4. This is always available as an alternative, and lenders charge whichever is greater. For variable-rate mortgages, the penalty is capped at 3 months' interest — no IRD applies.
When Is IRD vs. 3-Month Interest Applied?
- Early in the term: IRD is usually much larger — many months of rate differential remain
- Late in the term: IRD shrinks as months remaining decreases; may drop below 3-month interest
- When rates have risen: If current rates are higher than your contract rate, the IRD is zero (or negative) — you'd pay only 3 months' interest
- Variable rate: Always just 3 months' interest, no IRD
How to Reduce Your Penalty Before Breaking
- Make your maximum annual lump-sum prepayment before breaking — this reduces the outstanding balance (and therefore the penalty base)
- Ask your lender if they will waive or reduce the penalty for a renewal or blend-and-extend arrangement
- Consider porting the mortgage to a new property instead of paying it out
- Time the break for when rates are higher (IRD approaches zero when current rates exceed your rate)
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Get KOHO Free — Use Code 45ET55JSYAFrequently Asked Questions
Occasionally. If you're refinancing with the same lender or signing a new mortgage with them, they may absorb part of the penalty. It's always worth asking — especially if you're a high-value customer.
Yes. Most lenders calculate the penalty on your balance after applying any current-year prepayment allowance. Making your full annual lump sum before breaking reduces the penalty base dollar-for-dollar.
Sometimes. If you're refinancing to a higher balance, the lender may allow the penalty to be rolled into the new mortgage rather than paid out of pocket. This avoids the upfront cash requirement but increases your new mortgage balance.
Call your lender's mortgage department and request a "prepayment charge quote" for today's date. They are legally required to provide this. Get it in writing and ask them to explain the calculation methodology.