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Rescission of a Contract in Ontario: How to Unwind a Deal From the Start

Learn what rescission of a contract does in Ontario, when courts will actually allow it, and how it's different from terminating for a breach.

Litigation5 min readTSLBy the Treadstone Law team · OntarioUpdated 2026-07
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Key takeaways
  • Rescission is an equitable remedy that cancels a contract from its beginning — sometimes described as unwinding it "from the start" — and tries to restore both parties to the position…
  • Ontario courts will consider rescission where something undermined the basis on which a party agreed to the contract in the first place, including: - Misrepresentation — a false…

Most contract remedies look forward. Damages compensate you for a breach; terminating a contract stops future obligations. Rescission does something different — it tries to unwind the deal entirely, as though it had never been signed at all.

That makes rescission a powerful remedy, but also a limited one. Ontario courts don't grant it lightly, and it is realistically available only in specific circumstances.

This guide explains what rescission of a contract actually does, when it's available in Ontario, and how it differs from simply walking away from a contract after a breach.

What Rescission Actually Does

Rescission is an equitable remedy that cancels a contract from its beginning — sometimes described as unwinding it "from the start" — and tries to restore both parties to the position they were in before the contract existed. In practice, that usually means:

The goal is restitution: putting people back where they started, not compensating them for a loss going forward.

When Rescission Is Available

Ontario courts will consider rescission where something undermined the basis on which a party agreed to the contract in the first place, including:

This comes up often in disputes over the purchase or sale of a business, where pre-closing representations turn out to be false — see our buying and selling a business page for issues specific to those deals.

Rescission is not available simply because a contract turned out to be a bad deal, or because one side later regrets agreeing to it.

Rescission vs. Terminating for Breach

RescissionTermination for Breach
EffectUnwinds the contract from the startEnds the contract going forward only
What happens to past performanceReversed — money and property generally returnedGenerally stands; the injured party keeps what benefit it already received
Typical triggerMisrepresentation, duress, undue influence, unconscionability, or mistakeA serious breach of the contract's terms
Remedy soughtRestitution — put back to square oneDamages for the breach, going forward

Bars to Rescission

Even where the underlying grounds exist, a court can refuse rescission if:

How the Process Usually Works

  1. Identify the specific ground — misrepresentation, duress, undue influence, unconscionability, or mistake — and gather the evidence supporting it.
  2. Act promptly. Notify the other party that you consider the contract void and why, rather than continuing to perform under it.
  3. Try to negotiate a mutual unwinding, since litigating rescission can take time, and restitution is often easier to agree on than to fight over.
  4. If negotiation fails, a court application or action can seek a formal declaration of rescission along with orders for restitution.

Frequently asked questions

Can I rescind a contract just because I changed my mind?

No. Rescission requires a recognized legal ground — misrepresentation, duress, undue influence, unconscionability, or a qualifying mistake — not simply a change of heart or a deal that no longer looks attractive.

Is rescission the same thing as suing for damages?

No. Damages compensate you for a loss while leaving the contract, or its consequences, largely intact. Rescission tries to undo the contract altogether and return both sides to their starting position. In some cases, both remedies can be argued together, with a court choosing what fits the facts.

What if I already used the benefit of the contract?

That can affect whether rescission is still available. Continuing to use or accept the benefit of a contract after learning of the problem can be treated as affirming it, which weakens or defeats a later claim for rescission.

Do I need to go to court to rescind a contract?

Not necessarily at first — you can notify the other party and try to negotiate an unwinding directly. But if they disagree that grounds exist, a court will generally need to resolve the dispute and make the rescission effective.

This article is general information, not legal advice. Reading it does not create a lawyer-client relationship. Ontario laws, tax rates, and government programs change, and how the law applies depends on your specific facts. For advice about your situation, speak with a licensed Ontario lawyer. Treadstone Law is licensed by the Law Society of Ontario — reach us at 1-844-900-1070 or start a file online.

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