Interest: what you can claim and how to calculate it

Legal information, not legal advice. This guide and our free tools give legal information. They do not give advice about your case. A licensed lawyer can give legal advice.

The answer

You can claim interest on the money owed, from the day the claim arose until judgment. If your contract sets a rate, that rate applies; if not, the court rates apply.

The rates (2026)

• Prejudgment interest: 2.5% for cases started in any quarter of 2026.
• Postjudgment interest: 4.0% for judgments in any quarter of 2026.
• Q4 2026 (October 1 to December 31): 2.5% prejudgment, 4.0% postjudgment.

Prejudgment interest runs from the day the claim arose to the day of judgment. Postjudgment interest runs on the judgment amount until payment. The quarter in which you start the case sets your prejudgment rate. The rates change every quarter.

A simple example

You claim $10,000. The claim arose exactly 1 year before judgment. The court rate is 2.5%.

• Interest = $10,000 x 2.5% x 1 year = $250.
• The judgment can be $10,250, plus costs.

What to do

1. Check your contract for an interest rate.
2. If it has one, claim that rate on Form 7A.
3. If it does not, choose the Courts of Justice Act rate on Form 7A.
4. Write the date the claim arose. Interest runs from that date.
5. Bring a simple calculation to court: amount x rate x years.

Good to know

• The $50,000 limit does not include interest and costs.
• The rates change each quarter. Check the current rate before you file.
• After judgment, add postjudgment interest until the defendant pays.

Common mistakes

• Do not leave the interest section empty on Form 7A.
• Do not start the interest on the day you file. It runs from the day the claim arose.
• Do not use an old rate. Use the rate for the quarter you start the case.
• Do not claim a contract rate with no proof. The rate must be in the agreement.

When to get a lawyer

Get legal advice if the interest terms in your contract are not clear. Legal services provided by Mithril Law — Jonathan Kleiman, licensed Ontario lawyer.

Free tools

• Check if your claim is worth it: /check
• Write a demand letter: /demand-letter
• Fill in your court forms: /build/7a
• Calculate your deadlines: /calculators/deadlines