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Using a Counterclaim to Defend a Debt Claim in Ontario

Being sued for a debt in Ontario? Here's when a counterclaim lets a defendant turn the tables, how it works procedurally, and how it differs from a defence.

Litigation6 min readTSLBy the Treadstone Law team · OntarioUpdated 2026-07
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Key takeaways
  • - A counterclaim says: "Even putting that aside, you owe me money" — a separate claim, arising out of the same or a related situation, that you're entitled to pursue against the person…
  • A counterclaim fits naturally where the parties' dealings run in both directions.
  • In the Superior Court's ordinary civil process, a defendant who wants to counterclaim generally does so as part of responding to the claim — asserting the counterclaim alongside the…

Being served with a debt claim doesn't always mean you're purely on defence. If the person or business suing you also owes you something — for deficient work, an unpaid balance of their own, or a separate breach of the same contract — Ontario procedure lets you raise that as a counterclaim inside the very case being brought against you, rather than starting an entirely separate lawsuit.

Used well, a counterclaim can shift the whole tone of a case: instead of just defending, you're also pursuing your own recovery in the same proceeding. Used carelessly, it can turn a simple, cheap case into a longer, costlier fight for both sides. Knowing when it actually fits your situation — and when a straightforward defence is enough — is the first decision to make.

Counterclaim vs. Defence: Not the Same Thing

It helps to separate two different ideas that often get blurred together:

A defendant can raise both at once. You can dispute the plaintiff's claim on the merits while also asserting your own claim against them arising from the same dealings.

When a Counterclaim Actually Makes Sense

A counterclaim fits naturally where the parties' dealings run in both directions. Common scenarios include:

A counterclaim is not the right tool for grievances that have nothing to do with the plaintiff's claim or your relationship with them — an unrelated dispute usually needs its own, separate action.

How It Works Procedurally

In the Superior Court's ordinary civil process, a defendant who wants to counterclaim generally does so as part of responding to the claim — asserting the counterclaim alongside the statement of defence, rather than waiting and filing something separate later. In Small Claims Court, a defendant with their own related claim against the plaintiff can similarly bring it within the same proceeding, using the court's own process for that purpose, rather than starting an entirely new file.

Once a counterclaim is filed, the case effectively runs as two intertwined claims decided together:

  1. The plaintiff's original claim proceeds as normal, with the defendant (now also a plaintiff-by-counterclaim) responding to it.
  2. The counterclaim proceeds on its own footing — the original plaintiff must now respond to it, just as any defendant would.
  3. Both claims are typically heard and decided at the same time, often at the same trial or hearing, rather than as two separate proceedings on two separate timelines.
  4. The final result can go either way on each claim independently — a defendant could defeat the original claim, succeed on the counterclaim, both, or neither.

What to Weigh Before Counterclaiming

ConsiderationWhy it matters
Strength of your own claimA weak counterclaim adds cost and complexity without improving your position
Whether it's genuinely relatedClaims with no real connection to the plaintiff's case may not belong in the same proceeding
Added cost and timeA counterclaim generally extends the length and complexity of the case for both sides
Costs exposureIf you lose the counterclaim, you may face a costs award on it separately from the outcome of the original claim
Court levelA larger counterclaim amount could affect which court the whole matter needs to proceed in

A counterclaim is a genuine litigation strategy, not an automatic add-on — it's worth assessing on its own merits before filing, ideally with legal advice.

A Quick Comparison

Defence AloneDefence + Counterclaim
GoalDefeat the plaintiff's claimDefeat the plaintiff's claim AND recover your own damages
ComplexityGenerally simplerGenerally more involved — two claims to prove and defend
Possible outcomeYou owe nothing, or a reduced amountYou could owe nothing and also be awarded money from the plaintiff
RiskLowerHigher — you now bear the burden of proving your own claim too

Frequently asked questions

Do I have to file a counterclaim, or can I sue separately later?

You generally aren't required to counterclaim — you can often pursue a genuinely separate claim on its own later, subject to the usual limitation period rules. But raising a truly related claim in the same case is often more efficient than running two overlapping lawsuits at different times.

What if my counterclaim is for more money than the plaintiff is claiming from me?

That's possible, but a significantly larger counterclaim amount can affect procedural questions, including which court level is appropriate for the whole matter. This is worth flagging to a lawyer early rather than after filing.

Can the plaintiff drop their claim once I file a counterclaim?

A plaintiff may be able to discontinue their own claim, but that generally doesn't make your counterclaim disappear — it can typically continue on its own, since it's now effectively its own claim within the file.

Is set-off the same thing as a counterclaim?

Not exactly. Set-off is usually raised as part of your defence — arguing an amount should be deducted from what's claimed — while a counterclaim is a separate, affirmative claim for damages of your own. The two can overlap depending on the facts, which is exactly the kind of nuance worth reviewing with a lawyer.

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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