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Real Estate · Worksheet · 7 min

Breaking your mortgage: the penalty, the math and your options

How an Ontario prepayment penalty is calculated, what the Interest Act allows, and a worksheet for deciding whether breaking makes sense.

Last reviewed September 4, 2026 · Updated September 4, 2026

How an Ontario prepayment penalty is calculated, what the Interest Act allows, and a worksheet for deciding whether breaking makes sense.

⚖️ This is general information, not legal advice. It can't account for your specific situation. Use it to get oriented, then confirm the details with a licensed Ontario lawyer.

Breaking a closed mortgage before the end of its term means paying a penalty set by the contract. For a variable mortgage that is usually three months' interest; for a fixed mortgage it is usually the greater of three months' interest and the interest rate differential, and the differential can be many times larger. This worksheet walks through the calculation, the disclosure you are entitled to, the one rule that overrides the contract, and the columns to fill in before you decide. It explains; it does not recommend a product or a lender.


Step one: find the three documents

Step two: three months' interest

Take the balance you intend to pay off, multiply by your annual contract rate, divide by twelve, multiply by three. That is three months' interest. It is the usual penalty on a variable mortgage and the floor on most fixed ones.

If you have an unused prepayment privilege and the lender allows you to use it in the same transaction, reduce the balance first. Many lenders do not allow this on a full payout; ask in writing.

Step three: the interest rate differential

The differential compares your contract rate with the rate the lender says it would charge today for a term equal to your remaining term. The difference, applied to your balance for the months remaining, is the penalty. Two things swing the number. First, which rate the lender compares against: some use the posted rate for the comparison term, some the discounted rate, and some compare your original posted rate less your discount. Second, how many months remain; a differential with four years left is roughly four times one with a year left.

Lenders must disclose the method. If the figure on your payout statement does not match the method in your documents, ask for the calculation line by line. The penalty estimator on this site lets you test the lender's inputs.

Step four: the rule the contract cannot override

Section 10 of the Interest Act, mirrored in section 18 of Ontario's Mortgages Act, applies where a mortgage is not payable until more than five years after its date. Once five years have passed, an individual borrower can pay the balance plus three months' further interest and no more. It does not matter what the contract says. It does not apply to a five-year term, only to longer ones, and section 10(2) excludes mortgages given by corporations.

If your term is seven or ten years and you are past year five, the differential does not apply to you.

Step five: the worksheet

Step six: the options in order of cost

What happens after you decide

On a sale or refinance, the payout is made from your lawyer's trust account on closing, the lender is paid the statement figure plus per-diem, and it delivers a discharge that is registered on title. Check the parcel register a few weeks later. On a lump-sum payout without a sale, you pay the lender directly and ask who registers the discharge and when.


How Treadstone Law can help

The penalty is a number you can check, not a number you have to accept on faith. Get the documents, get the calculation, and put the columns side by side before you sign anything.

Treadstone Law handles real estate matters on a transparent flat fee, with online intake and a real lawyer on your file, across Ontario.


This is not legal advice

This guide is general information, not legal advice. Reading it does not create a lawyer-client relationship. Ontario laws and government programs change, and how the law applies depends on your specific facts. For advice about your situation, speak with a licensed Ontario lawyer. Treadstone Law is licensed by the Law Society of Ontario — reach us at 1-844-900-1070 or start a file online.

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Official resources

Government and regulator sources for this topic. Rules change — confirm the current position before you rely on it.

Official resources

Government and regulator sources for this topic. Rules change — confirm the current position before you rely on it.

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These guides are general information, not legal advice. Reading one does not create a lawyer–client relationship. For advice about your situation, speak with a licensed lawyer — call 1-844-900-1070.

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