Suing for Breach of Contract in Ontario: A Plain-Language Guide

When the other side breaks a contract — a service agreement, a real estate deal, a business partnership — the financial damage can be immediate and serious. Suing for breach of contract in Ontario is one of the most common reasons people end up in civil court, yet the process is poorly understood outside the legal profession. This guide explains what breach of contract actually means, what you need to prove, how a lawsuit unfolds, and what a court can award you if you win.

Nothing here replaces advice from a lawyer about your specific situation, but it will help you understand the landscape and ask the right questions before you decide how to proceed.

What Is a Breach of Contract?

A breach of contract occurs when one party to a valid, enforceable agreement fails to do what the agreement requires — either doing something they were not supposed to do, or failing to do something they were obligated to do.

Breaches come in different forms. A party may miss a payment deadline, deliver defective goods, abandon a project halfway through, or simply tell you outright they will not perform. Not every failure constitutes a legally actionable breach, and not every breach entitles you to the same remedies — but the starting point is always the same: there must be a contract, and someone must have violated it.

The Four Elements You Must Prove

Ontario courts apply a four-part test when evaluating a breach of contract claim. You, as the plaintiff, carry the burden of proving each element on a balance of probabilities — meaning it is more likely true than not.

1. A Valid Contract Existed

A contract does not have to be written to be enforceable, but you must show that:

• There was an offer made by one party
• The other party accepted that offer
• Both sides exchanged consideration (something of value — money, services, a promise to act or refrain from acting)
• Both parties had the capacity to contract (they were adults of sound mind, not under duress)

Verbal contracts can be enforceable in Ontario, though they are harder to prove. Written contracts, emails, text messages, and invoices all become important evidence.

2. The Defendant Failed to Perform

You must identify the specific obligation in the contract and show the defendant did not meet it. Courts look at the actual terms — not what you assumed or hoped — so clarity about what was promised matters enormously.

3. You Suffered a Loss

A technical breach that causes no actual harm will rarely justify a damages award beyond a nominal amount. You must be able to quantify what you lost: money paid and not returned, profit you expected but did not receive, costs you had to incur because of the breach.

4. The Breach Caused Your Loss

The defendant's failure must be the cause of your damages. If you would have suffered the same loss regardless of the breach, that weakens your claim.

Before You File: Steps Worth Taking

Litigation is expensive, slow, and uncertain. Before starting a lawsuit, consider the following steps — not just as a practical matter, but because courts expect parties to have attempted resolution.

1. Review the contract carefully. Look for dispute-resolution clauses (mandatory mediation, arbitration), notice requirements, and limitation periods. Missing a notice deadline can undermine an otherwise valid claim.

1. Send a formal demand letter. A letter clearly stating the breach, the amount owed, and a deadline for payment often resolves disputes without court involvement. It also documents that you tried.

1. Gather your evidence. Collect the contract, all correspondence, invoices, receipts, photos, and any other records that support your version of events. The stronger your paper trail, the better.

1. Check the limitation period. As of writing, Ontario's basic limitation period is two years from the date you knew (or ought to have known) you had a claim — verify this applies to your situation. Missing it can bar your claim entirely.

1. Get legal advice. A litigation lawyer can quickly assess whether your claim is viable, what it is worth, and whether the defendant is likely to have the means to pay a judgment.

Where to Sue: Choosing the Right Court

The dollar value of your claim determines which court you use.

• Small Claims Court handles claims up to a certain monetary ceiling (as of writing — verify the current limit). It is designed to be accessible without a lawyer, though a lawyer can help.
• Ontario Superior Court of Justice handles larger claims and more complex disputes. Procedures are more formal and costs are higher, but so are the stakes.

For business disputes involving significant amounts, Superior Court is typically the right forum. A lawyer can also advise on whether there are procedural advantages to one court over the other.

What Remedies Can You Get?

If you succeed, Ontario courts have several tools available:

Damages are the most common remedy. The goal is to put you in the position you would have been in had the contract been performed. Courts typically award:

• Expectation damages — the profit or benefit you expected from the contract
• Reliance damages — costs you spent in reliance on the contract
• Restitution — money you paid that the defendant must return

Specific performance is an order requiring the defendant to actually do what the contract required. Courts grant this sparingly — usually only when money is not an adequate substitute, such as in some real estate transactions.

Injunctions can stop a party from taking an action that would worsen the breach or cause irreparable harm pending trial.

One important limit: you have a duty to mitigate your losses. If you could have taken reasonable steps to reduce the damage caused by the breach and you did not, a court can reduce your damages award accordingly.

Frequently asked questions