Ontario postjudgment interest, explained

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.

For the ordinary rule, the date that matters is the date the order was made, as the Ministry's published guidance on the quarterly rates explains. That is often earlier than the date the order was entered or issued by the court office, which is an administrative step. Take the made date from the order or the reasons, note the entry date separately on the file, and check the order and any governing statute in case they direct something different.

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 is the definitions provision: it defines the postjudgment rate and the date by reference to which it is set. Postjudgment interest itself is awarded under section 129. The ordinary methodology for that calculation, reflected in the Ministry's published guidance, is simple interest - interest does not itself earn interest - unless a statute, an agreement or an order specifically provides for compounding.

Applying payments

The calculator on this site applies a partial payment first to accrued interest and then to principal. That is its default modelling assumption, chosen because it is a common convention, not a statement that the law requires payments to be allocated that way. The governing order, the parties' agreement, enforcement accounting or applicable law may require a different order, and the calculator lets you switch to principal-first. Whichever you use, say so when you give the figure to another party, because the two produce different balances.

What the interest actually runs on

Postjudgment interest runs on the amount payable under the order. Where the order includes costs and prejudgment interest, those amounts form part of the sum that carries postjudgment interest - so pulling only the damages figure off the front page of the order understates the balance.

Where costs are fixed later in a separate order, do not assume a single answer either way. The date from which those costs carry interest depends on the terms of the costs order and the rules and case law that apply to it; a costs order can also be expressed to run from the date of the original judgment. Read both orders and verify the position before you fix a date. What you should not do is roll amounts that may carry interest from different dates into one undifferentiated figure - run each amount over its own period, then add the results, so the assumption behind each one is visible and can be corrected.

Keeping a payment record you can defend

Interest is only as reliable as the payment history behind it. Keep a dated record of every amount received, from whatever source, including garnishment remittances and money paid into court. Two habits cause most disputes: crediting a payment on the day it cleared rather than the day it was received, and recording several payments as one lump sum at the end of the period. Both shift the balance that interest runs on. Where enforcement is underway, reconcile against the enforcement office's statement rather than your own ledger alone.

Verification workflow before you enforce or settle

1. Identify the date the order was made, as shown by the order or the reasons, and note it separately from the date the order was later entered or issued by the court office.
2. Identify the quarter in which the order was made and read the postjudgment rate for that quarter from the Ministry table, including its notes.
3. Confirm the base amount from the face of the order: damages, costs and any prejudgment interest included in it.
4. List every payment received, in date order, with its source, and confirm the total against your receipts.
5. Check the order and any settlement or payment agreement for interest terms or an allocation direction that displaces the default assumption.
6. Recalculate to the specific date you intend to quote - a payout figure is only valid for the day it was calculated to - and state that date whenever you give the number to another party.

When the ordinary rule can be displaced

Section 130 gives the court discretion to order a different rate or period in appropriate cases. Parties sometimes argue that a contractual interest rate continues to apply after judgment; whether it does is a legal question that turns on the wording of the contract, the terms of the order and the applicable case law, and it should not be assumed either way. Start with the order itself - some judgments specify a non-default rate on their face - and get advice where a contractual rate is in issue.

Worked workflow: turning a file into calculator inputs

Fictional teaching example - not legal authority. The record below is invented to show how a file is mapped onto the calculator's fields. It is not drawn from any court document, template or other source, and the rate is used as a stated assumption.

The record. A judgment is made on 15 January 2026 and entered by the court office on 20 January 2026. The order awards $8,000 in damages, $300 in costs and $120 in prejudgment interest. Nothing has been paid. The creditor wants a figure as at 16 March 2026. The rate assumed for the first quarter of 2026 is 4.0% per annum; you would confirm the actual published rate for that quarter on the Ministry table before using this.

Which date goes in. The start date is 15 January 2026, the date the order was made. The 20 January entry date is recorded on the file but is not entered into the calculator, because the ordinary rule keys off the made date.

What the base amount is. All three components of the order form the amount payable under it: $8,000 + $300 + $120 = $8,420. That single figure goes into the amount field. Splitting the damages off and running it alone would understate the balance.

Mapping to the fields. Calculation type: postjudgment. Amount owing under the order: $8,420. Annual rate: 4.0%, entered by hand and held fixed for the whole period. Judgment or order date: 15 January 2026. Calculation end date: 16 March 2026. Payments: none, so the allocation setting makes no difference here.

The arithmetic. 15 January 2026 to 16 March 2026 is 60 actual days (16 days remaining in January, 28 in February, 16 in March). Interest is $8,420 × 4.0% ÷ 365 × 60 = $55.36. The modelled total as at 16 March 2026 is $8,420.00 + $55.36 = $8,475.36.

Limits of this worked example. The figure is arithmetic on the inputs above, not a statement of what is owed. It assumes the 4.0% rate is the correct published rate for the quarter, that all three components of the order carry interest from 15 January 2026, that no payment or set-off has been received, and that no term of the order or other statute displaces the ordinary rule. Change any of those and the number changes. The total is good only for 16 March 2026; quote the date whenever you give the figure to anyone.

Next steps

With the rate, the base amount and the payment history settled, run the numbers through the Ontario Court Interest Calculator in postjudgment mode and keep the period-by-period breakdown with the enforcement file. If you also need the interest that accrued before judgment, that is a separate calculation on a different rate - see the prejudgment interest guide. Before issuing an enforcement step or accepting a payout figure, have the arithmetic and the entitlement checked by a lawyer or licensed paralegal.