The Other Side Breached Your Contract in Ontario: What to Do in the First 30 Days

The other side didn't deliver, didn't pay, or didn't do what the contract said they would — and now you're not sure what to do first. What you do in the days right after discovering a breach can shape whether you resolve this quickly or end up fighting about it later over things you could have locked down early.

Knowing what to do after a breach of contract in Ontario is less about knowing complicated law and more about discipline: document everything, avoid escalating unnecessarily, and don't sit on your rights. None of the steps below require you to have already decided whether you'll sue — they just protect your position either way.

This is a practical, roughly 30-day framework. The exact pace will depend on your situation, but the order matters more than the calendar.

First, Confirm It's Actually a Breach

Before you act, read the contract again. Confirm what was actually promised, what deadline or standard applied, and whether the other side's conduct genuinely falls short of it — as opposed to a delay or variation the contract itself allows for.

If the contract is silent or ambiguous on the point that matters, that ambiguity itself is worth flagging to a lawyer early, since it can change how strong your position is.

Right Away: Preserve the Paper Trail

• [ ] Save the original contract and any amendments, in the version actually signed.
• [ ] Save all related emails, texts, invoices, and messages — do not delete or edit anything, even informally.
• [ ] Take photos or screenshots if the breach involves physical work, a product, or something time-sensitive that could change or disappear.
• [ ] Write a short, dated note to yourself summarizing what happened and when you noticed it, while it's fresh.

Courts rely heavily on contemporaneous records. A clear paper trail built now is worth far more than your memory of events months later.

Avoid Making Things Worse

It's tempting to respond in kind — to withhold your own performance, badmouth the other side publicly, or fire off an angry message. Resist that. How you conduct yourself after a breach can affect your credibility and, in some cases, your own legal exposure if your reaction goes beyond what the contract or the law allows.

If you're unsure whether you're entitled to stop performing your own obligations in response to their breach, get advice before you do — treating a contract as over when you weren't entitled to can turn you into the party in breach.

Within the First Week or Two: Put It in Writing

Send a clear, professional written notice — not necessarily a formal demand letter yet — describing what happened, what the contract required, and what you expect to happen next. This does three things: it creates a record, it gives the other side a fair chance to fix things, and it often resolves the problem without anything further.

If the response is unsatisfactory, a formal demand letter, often from a lawyer, is usually the next step before considering court.

Take Reasonable Steps to Limit Your Losses

You generally have a duty to take reasonable steps to reduce the losses flowing from the other side's breach — sometimes called mitigation. That might mean finding a replacement supplier, re-listing a property, or otherwise limiting how much the breach costs you, rather than letting losses pile up while you wait to sue.

Failing to take reasonable mitigation steps can reduce what a court is later willing to award you, even if the breach itself is clear-cut.

Know Your Limitation Clock

Ontario's basic limitation period for starting most civil claims, including breach of contract, is 2 years — but that clock generally runs from when the claim was discovered, not necessarily from the date of the breach itself. If the breach wasn't obvious right away, discoverability can push the start date later.

Some contract-related claims are subject to shorter, more specific deadlines depending on what's involved, so don't assume you automatically have the full two years without checking.

Decide Your Next Move

By the time you've gathered your records, sent written notice, and taken reasonable mitigation steps, you're in a position to make an informed decision: accept a resolution, escalate to a formal demand letter, or move toward Small Claims Court, Simplified Procedure, or the Superior Court of Justice depending on the size and complexity of the claim.

Frequently asked questions