Being served with a lawsuit puts most people immediately on the defensive, and understandably so. A claim has been filed, deadlines are running, and the instinct is to focus entirely on responding to the allegations. What many defendants never realize is that Ontario law gives them a powerful option beyond simply defending: the right to bring their own claim right back. In Small Claims Court, this is called a Defendant’s Claim, and in the right circumstances it can completely change the dynamics of a case.

MTS Paralegal Services P.C. has represented both plaintiffs and defendants across Kitchener, Waterloo, Cambridge, Guelph, Hamilton, and Southwestern Ontario for over 20 years, and the Defendant’s Claim is one of the most underused tools available to people who find themselves on the receiving end of a lawsuit.

What Is a Defendant’s Claim?

A Defendant’s Claim is a claim brought by a defendant within an existing Small Claims Court action, using Form 10A under Rule 10 of the Rules of the Small Claims Court, O. Reg. 258/98. It allows a defendant to pursue their own claim against the plaintiff, against another defendant in the action, or against a third party who has not yet been named but who the defendant believes is responsible for some or all of the plaintiff’s alleged loss.

Consider a common example. A homeowner sues a contractor for allegedly defective renovation work. The contractor, however, was never paid the final invoice for that same project. Rather than defending the lawsuit and then starting a separate action to recover the unpaid invoice, the contractor can file a Defendant’s Claim within the existing case, and both disputes are resolved together. MTS Paralegal Services P.C. has examined the mechanics of this process in its earlier overview of how counterclaims operate in Ontario civil procedure, and the strategic value remains the same in every case: all related claims arising from the same events are heard at once.

The Deadlines That Decide Everything

Timing rules govern every stage of a Defendant’s Claim, and missing them has real consequences. Under Rule 10.01 of the Rules of the Small Claims Court, a Defendant’s Claim must be issued within 20 days after the day the Defence is filed. After that window closes, a Defendant’s Claim can only be issued with leave of the court, which means asking a judge for permission and explaining the delay.

Once issued, the claim must be served on every party against whom it is made, and official court guidance from the Ontario Superior Court of Justice confirms it must be served within six months of issuance. Any party who wishes to dispute the Defendant’s Claim then has 20 days after service to file a Defence using Form 9A. A party who fails to respond within that window risks judgment being obtained against them without further notice. These deadlines run alongside the two-year limitation period under the Limitations Act, 2002, which applies to a Defendant’s Claim just as it would to an independent action.

Why Filing a Defendant’s Claim Can Change the Entire Case

The strategic value of a Defendant’s Claim goes well beyond procedural convenience. A defendant who files a legitimate claim of their own transforms the negotiating landscape of the entire matter. The plaintiff who expected a one-sided proceeding now faces exposure of their own, and that shift frequently changes how settlement discussions unfold at the mandatory settlement conference stage.

There is also a practical efficiency benefit. Under Rule 10.04 of the Rules of the Small Claims Court, a Defendant’s Claim is tried together with the main action unless the court orders otherwise. One hearing, one set of evidence, one adjudicator resolving everything. That means no duplicate filing fees for a separate action, no second proceeding months later, and no risk of inconsistent results between two related cases. For defendants with genuine claims arising from the same dispute, the Defendant’s Claim is almost always the more efficient path.

What a Strong Defendant’s Claim Requires

A Defendant’s Claim is held to the same standard as any other claim before Small Claims Court. It must set out the full names of the parties, the nature of the claim in clear and concise language, the dates and places of the events involved, and the amount claimed or the relief requested. Supporting documents such as contracts, invoices, receipts, photographs, and correspondence should be attached, just as they would be for a Plaintiff’s Claim.

The claim must fall within the court’s $50,000 monetary jurisdiction, and it should be genuinely connected to a real loss rather than filed as a retaliatory tactic. An adjudicator can identify a claim with no merit quickly, and a weak Defendant’s Claim can damage the credibility of an otherwise strong defence. This is where an honest assessment from an experienced licensed paralegal matters most: knowing whether a Defendant’s Claim strengthens the position or undermines it is a judgment call that benefits from two decades of courtroom experience.

Served with a Claim? Move Fast and Move Smart

The 20-day windows in Small Claims Court do not pause while a defendant decides what to do. Anyone served with a Plaintiff’s Claim should immediately assess two questions: how to respond to the allegations, and whether they have a claim of their own that belongs in the same proceeding. Answering both questions early preserves every option. Answering only the first can mean leaving money on the table or facing a second round of litigation later.

Timothy Ellis of MTS Paralegal Services P.C. has spent over 20 years helping defendants turn lawsuits into opportunities to assert their own rights. From preparing the Defence and Defendant’s Claim to representation at the settlement conference and trial, the firm handles every stage with precision. Anyone who has been served should reach out through the contact page or call (226) 444-4882 before the clock runs out.

Being sued does not make you the loser. Sometimes it makes you the plaintiff too.

Small Claims Court… It’s What We Do.