A mortgage prepayment penalty is a charge a lender may apply when you break a closed mortgage early or exceed your prepayment privileges. Fixed-rate closed mortgages usually use the greater of three months' interest or the interest-rate differential, while variable-rate closed mortgages typically use three months' interest.
A mortgage prepayment penalty is the charge a lender can apply when you pay off a closed mortgage before the end of its term, switch lenders before maturity, or prepay more than your contract allows. In Canada, the two most common penalty formulas are three months' interest and the interest-rate differential (IRD). Which one applies depends mainly on whether your mortgage is fixed or variable, and on the wording of your mortgage contract.
This guide explains how each method is calculated, why fixed-rate penalties can be far larger when interest rates have fallen, and what to check before you break a mortgage. It is general information, not financial advice. Your lender's exact formula and your mortgage documents control the final number.
| Mortgage type | Typical prepayment penalty approach | What drives the cost |
|---|---|---|
| Closed fixed-rate | Greater of three months' interest or the interest-rate differential | Your contract rate, the lender's current comparable rate, your balance, and the time left in the term |
| Closed variable-rate | Usually three months' interest | Your outstanding balance and current rate |
| Open fixed or variable | Usually no prepayment penalty | Often a higher interest rate instead |
The Financial Consumer Agency of Canada — mortgages explains that mortgage terms and conditions, including prepayment charges, are set out in your mortgage contract. That contract is the starting point for any estimate.
How three months' interest is calculated
Three months' interest is the simpler of the two common penalty methods. In broad terms, the lender takes your outstanding balance, applies your mortgage interest rate, and calculates what three months of interest would be. A simplified formula is:
Outstanding balance × annual interest rate ÷ 12 × 3
For example, if the balance were $300,000 and the rate were 5%, three months' interest would be roughly $3,750: $300,000 × 0.05 = $15,000 per year, divided by 12 = $1,250 per month, multiplied by 3 = $3,750. That is only an illustration. Lenders may use different compounding methods, posted rates, or contract-specific definitions, so the actual figure can differ.
Three months' interest is most commonly associated with closed variable-rate mortgages. It can also apply to a closed fixed-rate mortgage when it produces a larger penalty than the IRD — although in a falling-rate environment, the IRD often produces the larger number.
How the interest-rate differential works
The interest-rate differential, or IRD, is designed to compensate the lender when you break a fixed-rate mortgage and current interest rates are lower than your contract rate. The lender compares your mortgage rate with a current rate for a term similar to the time remaining on your mortgage. If your rate is higher, the difference is used to calculate the penalty.
A simplified IRD illustration can help. Suppose you have $300,000 left on a fixed mortgage at 5%, with three years remaining. If the lender's current comparable rate were 3%, the difference would be 2 percentage points. A rough IRD calculation would be $300,000 × 0.02 × 3 = $18,000. Because $18,000 is greater than three months' interest of $3,750, the penalty in this simplified example would be based on the IRD. Again, real calculations vary by lender.
Several details can change the result:
- Which rates are compared. Some lenders compare your contract rate to their posted rate; others use a discounted rate or a reinvestment rate. The choice can significantly change the penalty.
- The remaining term. A longer remaining term usually means a larger IRD because the rate difference is multiplied over more months or years.
- The size of the rate gap. The further current rates have fallen below your contract rate, the larger the IRD can be.
- The outstanding balance. A larger balance increases both three months' interest and the IRD.
Because the IRD depends on current rates, it can change over time. The Bank of Canada — interest rates publishes policy and market rate information that gives context for where rates have moved, but your lender's posted or discounted mortgage rates are the ones that matter for the penalty quote.
Why fixed and variable mortgages are treated differently
With a closed fixed-rate mortgage, the lender has committed to a set rate for a set term. If you break the mortgage when rates have fallen, the lender may have to lend that money out again at a lower rate. The IRD is intended to recover some of that difference. That is why fixed-rate penalties can be much larger than three months' interest.
With a closed variable-rate mortgage, the interest rate typically moves with the lender's prime rate. The lender is not locked into the same fixed spread for the whole term, so the prepayment charge is usually based on three months' interest rather than an IRD. That does not make variable penalties small in every case: three months' interest on a large balance can still be thousands of dollars.
Open mortgages work differently. They usually allow you to prepay or pay off the mortgage without a prepayment penalty, but they often carry a higher interest rate. Borrowers who expect to sell or refinance soon sometimes compare the higher rate of an open mortgage with the potential penalty on a closed mortgage. The Canada Mortgage and Housing Corporation provides general information on mortgage types and housing finance in Canada.
What can trigger a prepayment penalty
A penalty can be triggered in more situations than simply paying off the entire mortgage. Common triggers include:
- Selling your home before the mortgage term ends and paying off the mortgage from the sale proceeds.
- Refinancing or switching lenders before maturity, unless the new lender or your existing lender arranges an exemption.
- Paying more than your annual prepayment privilege. Many mortgages allow you to increase payments or make lump-sum prepayments up to a set limit, often a percentage of the original principal. Going over that limit can trigger a charge on the excess.
- Changing the mortgage term or converting a variable mortgage to a fixed mortgage in some contracts.
- Assuming the mortgage or adding or removing a borrower, depending on the lender's rules.
Some lenders allow you to port your mortgage to a new property, or to blend and extend your mortgage into a new term, without paying a full prepayment penalty. These options are not automatic, and they usually come with conditions. It is worth asking about them before you list your home or sign a refinancing agreement.
How to estimate and compare your penalty exposure
Start by reading your mortgage contract and looking for the prepayment charge section. Then ask your lender for a written penalty quote. A written quote is more reliable than a rough online estimate because it uses the lender's own formula and current rates.
Useful steps include:
- Confirm whether your mortgage is open or closed, fixed or variable.
- Find out your annual prepayment privilege and how much room you have left this year.
- Ask whether the penalty is calculated on the outstanding balance or the original principal.
- Ask which rate the lender uses for an IRD comparison.
- Ask whether porting, blending and extending, or waiting until renewal would reduce or eliminate the charge.
- Compare the penalty with the interest savings or other benefits of breaking the mortgage early.
The Financial Consumer Agency of Canada offers consumer information on loans and borrowing that can help you understand your rights and responsibilities. If you are co-signing a mortgage or helping someone qualify, the same contract rules apply to the penalty calculation. See our guide to what a co-signer is for background on how co-signing affects mortgage obligations.
Common mistakes to avoid
- Assuming the penalty is always three months' interest. On a closed fixed-rate mortgage, the IRD can be much larger when rates have fallen.
- Ignoring the remaining term. A long remaining term increases the IRD because the rate difference is applied over more time.
- Overpaying without checking the privilege limit. A lump-sum payment that exceeds the annual limit can trigger a penalty on the excess.
- Relying on a verbal estimate. Ask for the penalty calculation in writing, including the rates used.
- Forgetting porting or blend-and-extend options. These can sometimes reduce or eliminate the penalty if you are moving or staying with the same lender.
- Breaking a mortgage without comparing the full cost. The penalty is only one part of the decision; compare it with the new rate, fees, and the time left in the term. A loan payment calculator can help you compare monthly payments, and our page on bad credit loans explains how credit history can affect borrowing options.
Prepayment penalties are not one-size-fits-all. Two borrowers with the same balance and term can receive different quotes if their contracts use different rate comparisons. The key is to check your own mortgage documents, request a written penalty quote from your lender, and compare that number with the cost of staying in the mortgage until renewal. For more general mortgage information, see the Financial Consumer Agency of Canada — mortgages page.