Can I collect interest on money someone owes me in Ontario if there was no agreement about interest?

Yes, Ontario courts have the authority to award interest on money judgments even when the underlying agreement did not specify an interest rate. The Courts of Justice Act sets out a framework for prejudgment interest (interest that accrues from the date the cause of action arose until the date of judgment) and post-judgment interest (interest that accrues after the judgment until it is paid).

The specific rate for prejudgment interest where the contract is silent is set by regulation and changes periodically. Courts have discretion to vary the rate based on the circumstances of the case.

Post-judgment interest also accrues at a rate set by regulation. The practical effect is that the longer a judgment remains unpaid, the more the debtor owes in total.

If your agreement with the debtor included a specific interest clause — for example, specifying 18% per annum on overdue balances — the court will generally apply that rate as long as it does not violate any applicable legal limit. Consumer protection legislation may cap interest rates on certain types of consumer credit.

When calculating what you are owed, include the principal, any contractually agreed interest, and then the statutory interest available under the Courts of Justice Act. A lawyer can help you calculate the total claim accurately before filing.