Unjust Enrichment Claims in Ontario: When Someone Benefits at Your Expense

Sometimes a person ends up better off because of something you did or gave, and there is no fair or legal reason they should be allowed to keep that benefit. Maybe you paid a contractor who walked off the job. Maybe you transferred money to someone under a mutual misunderstanding. Maybe you provided services to a person who died, and their estate is refusing to compensate you. These scenarios — and many others — can give rise to an unjust enrichment claim in Ontario.

Unjust enrichment is a foundational legal concept that exists to prevent one party from keeping a benefit they received in circumstances where justice demands it be returned or compensated. Unlike breach of contract (which requires a valid agreement) or negligence (which requires carelessness causing harm), unjust enrichment is its own independent cause of action grounded in equity and restitution law.

The Three-Part Test

Canadian courts (including Ontario courts) apply a well-established three-part test for unjust enrichment. To succeed, a plaintiff must show:

1. Enrichment of the Defendant

The defendant received some benefit — money, property, services, or something else of value. The benefit does not have to be money; it could be work you performed, an improvement to their property, or goods you delivered.

2. A Corresponding Deprivation of the Plaintiff

Your conferral of the benefit came at a cost to you. There must be a direct link between what the defendant gained and what you lost. If you were enriched too (for example, you received something in return), that exchange is taken into account.

3. No Juristic Reason for the Enrichment

This is the most nuanced element. The defendant's retention of the benefit must be unjust — meaning there is no legal or equitable reason that justifies them keeping it. A juristic reason would exist if:

• There was a valid contract entitling the defendant to the benefit
• The plaintiff made a gift (freely and intentionally transferred the benefit without expectation of return)
• There was another applicable rule of law that justifies the enrichment

If none of these apply, the enrichment is "unjust" and the plaintiff may recover.

Common Situations Involving Unjust Enrichment

Paid Services Not Completed

You paid a supplier or contractor a deposit, they did part of the work and disappeared. There may be a contract claim and an unjust enrichment claim overlapping here. Courts often allow both to be pleaded.

Services Provided Without a Contract

You provided valuable services (caregiving, farm work, renovation labour) with a reasonable expectation of compensation, but no formal contract existed and the other party refuses to pay. This is a classic quantum meruit ("what one has earned") situation — a form of unjust enrichment.

Money Paid by Mistake

You transferred funds based on a factual error — wrong account, double payment, incorrect invoice. If the recipient has no contractual right to the money, you can generally recover it as unjust enrichment.

Cohabiting Couples and Relationship Breakdown

Unjust enrichment frequently arises when unmarried couples separate. One partner may have contributed labour, money, or care that improved the other's property or financial position. Since unmarried spouses in Ontario do not have the same automatic property rights as married spouses, unjust enrichment (and the resulting constructive trust remedy) is sometimes the path to a fair division of assets.

Deceased Estates

If you provided services to someone who has died (a relative, a close friend) with an expectation of payment or compensation from the estate, and the estate refuses to acknowledge the arrangement, an unjust enrichment claim may apply.

The Remedy: Restitution or Constructive Trust

If unjust enrichment is established, the court can order one of two types of remedy:

Monetary Restitution

The defendant pays you the value of the benefit they received. The court quantifies this based on the market value of the services or the amount of money transferred (not your subjective loss or expectation of profit).

Constructive Trust

Where a monetary award is insufficient — typically where the unjust enrichment is connected to specific property (like real estate) — the court may impose a constructive trust, declaring that the defendant holds some or all of the property in trust for the plaintiff. This gives the plaintiff a proprietary interest, not just a debt.

Constructive trust is particularly significant in property disputes between separated common-law partners.

How Unjust Enrichment Relates to Contract Claims

Unjust enrichment is generally not available where a valid contract governs the same subject matter. If you have a contract and the other side breached it, your remedy is in contract law. Unjust enrichment fills the gap where:

• No contract was formed
• The contract is void or unenforceable
• The contract does not cover the specific situation at issue

It is common for plaintiffs to plead both breach of contract and unjust enrichment as alternatives, letting the court determine which applies on the facts.

Limitation Periods

Unjust enrichment claims in Ontario are subject to the two-year basic limitation period — as of writing, starting from the date the plaintiff discovered (or ought to have discovered) the claim. Verify the current limitation period with a lawyer. In cases involving ongoing relationships (like cohabiting partners), determining when the "clock" started running is itself a legal question.

Frequently asked questions