Remaining Duration and IRD Calculation
In the interest rate differential (IRD) formula, the remaining term is a direct multiplier. The formula is: (Contractual rate - Comparison rate) x Remaining balance x Number of months remaining / 12. Each passing month reduces this multiplier by one unit, proportionally decreasing the penalty.
A borrower who breaks their mortgage at the beginning of a 5-year term faces an IRD calculated on nearly 60 months. The same borrower, with the same rate gap and balance, would pay a considerably lower penalty by waiting until only 18 to 24 months remain. This timing strategy is one of the most powerful levers to reduce the penalty.
The Optimal Waiting Strategy
The profitability analysis must balance the penalty reduction against the additional interest cost paid while waiting. If your current rate is 5.50% and the available rate is 3.50%, each month of waiting costs approximately the rate gap on your balance. There is an optimal tipping point that your mortgage broker can calculate.
Special Cases
- Some lenders round the remaining duration to the nearest standard term (1, 2, 3, 4 or 5 years), which can change the comparison rate used.
- When the IRD drops below the three months' interest threshold, the penalty stays at three months: that is the floor.
- For an open term or variable rate, the remaining duration has no impact on the penalty.
- If you are approaching the last month of the term, most lenders allow penalty-free repayment within the last 30 to 120 days.
As an AMF-certified mortgage broker in Quebec, it is essential to integrate the remaining duration variable into any refinancing analysis. OSFI requires fédéral lenders to provide a penalty estimate including this component, facilitating informed decision-making.