Mortgages
Mortgage Penalties in Canada: IRD vs Three Months’ Interest, Explained
· 7 min read · Rates and rules verified September 2026
Breaking a Canadian mortgage before the end of its term almost always triggers a prepayment penalty. The penalty itself is not the interesting part — how it is calculated is. Two borrowers with identical balances can face wildly different penalties depending on whether their lender uses posted rates or discounted rates in the math, and on how much time is left in the term. Here is how it works, and how to pay less of it.
The two calculations behind every fixed-mortgage penalty
For a fixed-rate mortgage, Canadian lenders calculate two numbers and charge you the greater of the two:
- Three months’ interest on your outstanding balance at your contract rate.
- The interest rate differential (IRD) — the lender’s estimate of the interest income it loses because you are paying out early.
Three months’ interest is simple arithmetic: balance × contract rate ÷ 4. On a $400,000 balance at 5.50%, that is roughly $5,500. The IRD is where things get expensive, and where the fine print matters most.
How the IRD actually works
The IRD tries to answer a fair question: if the lender takes your $400,000 back today and re-lends it for the remainder of your term, how much interest does it lose compared to keeping your mortgage? The formula is:
IRD = (your contract rate − the lender’s current comparable rate) × balance × years remaining
The “comparable rate” is the lender’s current rate for a term closest to the time remaining on yours. If you have two years left on a five-year fixed, the lender compares against its current two- or three-year rate.
Here is the catch: lenders do not all pick that comparable rate the same way.
Why Big Six penalties are often bigger than monoline penalties
Canada’s Big Six banks generally calculate the IRD using their posted rates — the high advertised rates almost nobody actually pays. Monoline lenders (companies like MCAP, Merix, and RMG that only do mortgages) typically use discounted rates — the rates they are genuinely offering today.
Because posted rates sit well above discounted rates, the gap between your contract rate and the comparison rate looks larger at a Big Six bank, and the IRD penalty comes out larger. It is entirely normal for the same mortgage to carry a penalty thousands of dollars higher at a major bank than at a monoline, for this reason alone. This is one of the least understood costs in Canadian mortgages, and it is worth asking about before you choose a lender — not just the rate, but how the lender calculates IRD.
A worked example. You owe $400,000 with two years left on a five-year fixed at 5.50%.
Three months’ interest: $400,000 × 5.50% ÷ 4 = $5,500.
IRD, if the comparable rate is 4.00%: (5.50% − 4.00%) × $400,000 × 2 years = $12,000.
Your penalty is the greater amount: $12,000.
Variable-rate mortgages are simpler
On a variable-rate mortgage, the penalty is almost always just three months’ interest — no IRD calculation at all. That makes variable penalties dramatically smaller and more predictable than fixed penalties, especially when rates have fallen since you signed. It is one of the genuine, underappreciated advantages of going variable: your exit cost stays low.
| Situation | Typical penalty |
|---|---|
| Fixed rate, rates fell since you signed | Greater of IRD or 3 months’ interest — often the IRD, and often large |
| Fixed rate, rates rose since you signed | Usually just 3 months’ interest (IRD can be zero or negative) |
| Variable rate | Three months’ interest in most cases |
| Within weeks of renewal | Often minimal — IRD shrinks as remaining term shrinks |
Five legitimate ways to reduce the penalty
- Use your prepayment privileges first. Most mortgages let you make a lump-sum prepayment of 15–20% of the original balance each year, plus increase your regular payment. Doing this before you discharge the mortgage shrinks the balance the penalty is calculated on.
- Port your mortgage. If you are selling and buying, many lenders let you transfer the existing mortgage — rate, balance, and remaining term — to the new property, avoiding the penalty entirely. Ask about the port window (often around 90 days between sale and purchase).
- Blend and extend. Staying with the same lender but wanting a new rate or term? A blend-and-extend combines your current rate with today’s rate into a new term, usually with little or no penalty.
- Time the break. The IRD falls as your remaining term shortens. If you can wait a few months, get a fresh penalty quote — the number drops every month you get closer to renewal.
- Ask for a discretionary reduction. Lenders occasionally reduce penalties to keep your business, especially if you are refinancing with them rather than leaving. It costs nothing to ask, and the answer is sometimes yes.
When breaking still makes sense
A penalty is not automatically a reason to stay put. If today’s rates are enough lower than your contract rate, the interest you save over the new term can exceed the penalty — sometimes by a wide margin. The right question is never “what is the penalty?” but “what is the penalty minus what I save?” That break-even calculation, done honestly with your real numbers, is the whole decision.