Mortgage break penalty in Canada: how IRD is calculated
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By Editorial team
A Canadian borrower with a $500,000 fixed-rate mortgage at 5.50% and 18 months remaining in their term faces an IRD penalty of roughly $10,800 if they break and refinance today at a lower rate. That is more than the interest savings from the rate drop over the remaining 18 months - which means breaking does not pay off within the current term. This article explains how that number is calculated, why it is often larger than borrowers expect, and how to model whether the savings on a new mortgage eventually exceed the cost of leaving early.
The scenario modeled
Both tabs use a $625,000 purchase with 20% down ($500,000 mortgage), Canadian semi-annual compounding, 25-year amortization, and a 5-year term. Tab A keeps the original 5.50% rate for the full amortization. Tab B refinances to 4.00% - roughly what the lender's current posted 1-year rate might be in the worked example below. The comparison shows the monthly payment relief and total interest savings a borrower would get if they broke their mortgage and held the new rate for the full remaining amortization.
| Input | Keep: 5.50% fixed | Refinance: 4.00% fixed |
|---|---|---|
| Purchase price | $625,000 | $625,000 |
| Down payment | $125,000 (20%) | $125,000 (20%) |
| Mortgage amount | $500,000 | $500,000 |
| Rate | 5.50% fixed | 4.00% fixed |
| Amortization | 25 years | 25 years |
| Compounding | Semi-annual (Canadian) | Semi-annual (Canadian) |
| Payment frequency | Monthly | Monthly |
The findings
Dropping from 5.50% to 4.00% on a $500,000 Canadian mortgage saves $422/month in P&I and reduces total interest over 25 years by $126,557. Those lifetime savings are large - but the relevant comparison when deciding whether to break is not the full 25-year picture. It is whether the monthly savings over the remaining term exceed the penalty you pay today. On 18 months remaining at a $10,800 IRD penalty, they do not.
| Keep: 5.50% fixed | Refinance: 4.00% fixed | Difference | |
|---|---|---|---|
| Monthly P&I | $3,052 | $2,630 | $422/mo less |
| Total interest (25 yr) | $415,587 | $289,030 | $126,557 less |
| Schedule length | 300 months (25 years) | 300 months (25 years) | Same |
How IRD is calculated in Canada
There are two possible penalties when you break a Canadian mortgage early. The lender always charges whichever is larger:
- Three months of interest - applied to variable-rate mortgages and some short fixed terms. On $480,000 at 5.50%, three months of interest is about $6,600.
- Interest Rate Differential (IRD) - the standard penalty for fixed-rate mortgages. It is almost always larger, which is why it applies in most break scenarios.
The IRD formula is:
IRD = (contract rate - comparison rate) x outstanding balance x remaining years
The comparison rate is the lender's current posted rate for the term closest in length to your remaining term - not the discounted rate you actually received. This distinction matters a lot. If you received a discount of 1.25% below posted when you signed, and the lender's current posted 1-year rate is 4.00%, the comparison rate the lender uses is 4.00%, not 4.00% minus your original discount.
Worked example
A borrower has a $500,000 mortgage at a 5.50% contract rate with 18 months remaining. After 3.5 years of payments, the outstanding balance is approximately $480,000. The lender's current posted rate for a 1-year term (closest to 18 months) is 4.00%.
IRD = (5.50% - 4.00%) x $480,000 x 1.5 years
IRD = 1.50% x $480,000 x 1.5
IRD = $10,800
Now compare to the three-month interest alternative: 5.50% x $480,000 / 12 x 3 = $6,600. The IRD ($10,800) is larger, so that is the penalty charged.
Monthly payment savings from refinancing to 4.00%: roughly $426/month (as shown in the findings table above, applied to the full $500k original loan). Over 18 remaining months, that is about $7,668 in savings - less than the $10,800 penalty. Breaking does not pay off within the term.
If the borrower is two years into a 5-year term (36 months remaining), the same formula gives: (5.50% - 4.00%) x $460,000 x 3.0 = $20,700 - and the monthly savings over 36 months are roughly $15,300. Still underwater, but getting closer. At 48 months remaining, the calculus begins to flip depending on the rate differential.
Source: Financial Consumer Agency of Canada, "Prepayment privileges and charges," accessed June 2026. URL: https://www.canada.ca/en/financial-consumer-agency/services/mortgages/break-mortgage-contract.html
When breaking makes sense - and when it does not
Breaking makes financial sense when: the interest savings on the new lower rate over the remaining term exceed the IRD penalty. The earlier in a term you break, the more months remain to recoup the penalty. A drop of 1.50% on a large balance with 3+ years left can justify the penalty, particularly if you plan to hold the new mortgage to its full term.
It does not make sense when: you are in the final 12-24 months of your term (the penalty window is too short), when the rate difference is less than 1%, when you plan to sell within the next year, or when you have not confirmed the actual penalty figure directly with your lender. The formula above is illustrative - lenders calculate it slightly differently, and some use a discounted comparison rate that changes the result materially. Always get the actual penalty disclosure in writing before deciding.
Variable-rate mortgages: If you are on a variable rate, your penalty is simply three months of interest regardless of how rates have moved. On a $480,000 mortgage at a current rate of 4.45%, that is about $5,340. Breaking a variable-rate mortgage is nearly always cheaper than breaking a fixed-rate one at the same balance.
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Frequently asked questions
- What is an IRD penalty on a Canadian mortgage?
- IRD stands for Interest Rate Differential. It is the penalty a lender charges when you break a fixed-rate mortgage before the term ends. The penalty compensates the lender for the interest they lose by re-lending your money at a lower current rate. For most fixed-rate mortgages in Canada, the IRD is the larger of the two standard penalty types - the other being three months of interest.
- How is the IRD calculated?
- The formula is: (your contract rate minus the lender's current posted rate for a term closest to your remaining term) multiplied by your outstanding balance, multiplied by the remaining term in years. The key variable is which "comparison rate" the lender uses. Banks typically use their posted rate, not the discounted rate you actually received, which makes the penalty larger than most borrowers expect.
- Why is my actual penalty higher than what I calculated?
- Most major Canadian banks calculate the IRD using their posted rate as the comparison rate, not the discounted rate they offered you. Because borrowers usually receive a discount of 1-2% below posted, using the posted rate as the comparison reduces the spread - but some lenders use a "discounted comparison rate" which inflates the penalty. Always ask your lender for the exact calculation methodology and the specific comparison rate they will use before deciding to break.
- Does breaking a variable-rate mortgage trigger an IRD penalty?
- No. Variable-rate mortgages in Canada (both VRM and ARM types) are subject only to a three-month interest penalty when broken. IRD applies to fixed-rate mortgages. This is one reason some borrowers prefer variable-rate products when they anticipate needing flexibility before term end.
- How do I decide if breaking my mortgage is worth the penalty?
- Compare the IRD penalty against the monthly interest savings on the new lower rate, multiplied by the number of months remaining in your term. If the penalty exceeds the term savings, breaking does not pay off within the current term. If you plan to stay in the home beyond the term, you can extend the break-even calculation over more months - but you need the penalty number from your lender first, since the formula varies.