What postjudgment interest is
Postjudgment interest is interest that accrues on an unpaid judgment after it is entered, until it is paid. Section 129 of the Courts of Justice Act sets the default rule for Ontario courts.
When it starts and stops
Postjudgment interest runs from the date of the order to the date of payment. If the debtor pays part of the judgment, interest continues to accrue on the unpaid balance.
Which rate applies
The default rate is set by reference to the bank rate at the end of the first day of the last month of the quarter preceding the quarter in which the order was made. Ontario publishes the quarterly table online. Use the rate for the quarter the judgment was granted - not the quarter of payment or the quarter of calculation.
Simple interest, not compound
Section 127 provides for simple interest. Interest does not itself earn interest, unless a statute, agreement, or order specifically provides for compounding.
Applying payments
When a partial payment is received, apply the payment first to accrued interest and then to principal, unless the order, the parties' agreement, or applicable law directs otherwise. Reducing principal this way reduces the interest that accrues going forward.
When the ordinary rule can be displaced
Section 130 gives the court discretion to order a different rate or period in appropriate cases. A contract can also provide a different rate that continues past judgment where the debt merges into the judgment. Check the order itself - some judgments specify a non-default rate on the face of the order.
Worked example
Facts. Judgment for $10,000 is entered on 1 October 2025, with no added costs or prejudgment interest for this simplified illustration. The postjudgment rate published for the fourth quarter of 2025 is 4.0% per annum. The debtor pays $2,000 on 1 April 2026. The creditor calculates the balance as of 1 October 2026.
Scope of the base amount. Under the official Ontario method, postjudgment interest accrues on the total judgment amount, which includes any awarded costs and prejudgment interest. This example uses $10,000 only to keep the arithmetic transparent.
1 October 2025 to 1 April 2026. 182 actual days on $10,000 at 4.0% = $10,000 × 0.04 × (182 ÷ 365) = $199.45 in interest.
Applying the $2,000 payment (interest-first). This example follows the same default modelling assumption as the Ontario Court Interest Calculator: a partial payment is applied first to accrued interest, and any remainder reduces principal. The $2,000 payment first clears the $199.45 of accrued interest; the remaining $1,800.55 reduces principal to $8,199.45. The order, the parties' agreement, enforcement accounting, or applicable law can require a different allocation.
1 April 2026 to 1 October 2026. 183 actual days on $8,199.45 at 4.0% = $8,199.45 × 0.04 × (183 ÷ 365) = $164.44. Modelled balance owing on 1 October 2026 is $8,199.45 + $164.44 = $8,363.89.
Related calculators
Official sources
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