Ontario Post-Judgment Interest Calculator

Postjudgment interest compensates a successful party for the time between the date the court makes its order and the date the judgment is paid. In Ontario it is awarded under section 129 of the Courts of Justice Act and calculated as simple interest at the quarterly rate published by the Ministry of the Attorney General.

For the third quarter of 2026, the postjudgment interest rate in Ontario is 4% per annum. This is the official rate published by the Ministry of the Attorney General, and it is read from the same rate table the calculator above uses so the two stay consistent.

This calculator sets the rate using the date of the order — the quarter in which the judgment was made. That single rate then applies for the whole period: interest runs from the date of the order until the judgment is paid.

It is simple interest by default — it does not accrue interest on itself. Compound interest is only available in limited circumstances, such as where a contract pleaded in the claim provides for it.

Under section 129 of the Courts of Justice Act, postjudgment interest runs from the date of the order. It is calculated on the amount owed under the order and continues to accrue until the judgment is paid in full.

Yes. The Small Claims Court is a branch of the Superior Court of Justice, so section 129 applies. A Small Claims Court judgment accrues postjudgment interest from the date of the order until it is paid.

Multiply the judgment amount by the annual postjudgment rate, divide by 365, and multiply by the number of days from the date of the order to the date of payment. It is simple interest, so it does not compound. The calculator above applies the official rate for you.

Prejudgment interest covers the period before the order (from when the cause of action arose to the date of judgment). Postjudgment interest runs after the order on the unpaid judgment until it is paid. They use different rate tables set quarterly by the Ministry of the Attorney General.

Yes. It continues to accrue on the outstanding amount from the date of the order until the judgment is satisfied in full, which increases what a debtor ultimately owes the longer they delay.

Postjudgment interest is generally calculated on the total amount ordered, which can include the principal, prejudgment interest, and costs that form part of the judgment. Confirm exactly what your order says is owing, since the wording of the judgment controls.

Yes. Under section 130 of the Courts of Justice Act, the court has discretion to vary the rate or the period in appropriate circumstances, taking into account market rates and the conduct of the parties.

It can. Where a contract provides for a specific interest rate, that rate may apply to a judgment on the contract instead of the default Courts of Justice Act rate. Enter the applicable rate where your agreement specifies one.

It adds ongoing cost for a debtor who does not pay, which can pressure settlement. When you enforce a judgment — through garnishment, a writ of seizure and sale, or a debtor examination — the accruing postjudgment interest is added to what you can collect.

No. Postjudgment interest accrues automatically by operation of section 129 from the date of the order — you do not file a separate application for it. You do, however, need to account for it correctly when you calculate the total owing for enforcement.

On small amounts the interest may be modest, but it still adds up over time and signals that delay has a cost. Whether it is worth aggressive enforcement depends on the debtor's ability to pay — something a brief consultation can help you assess.