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Ontario Counterclaim Calculator

Being sued in Small Claims Court and want to counterclaim? See your net position and check both claims against Ontario's $50,000 monetary jurisdiction.

Estimate only — not legal advice. Jurisdiction rules for counterclaims are technical.
Reviewed by Ryan Manilla, BA, JDFounder & Managing Lawyer, Legal Solutions Law Firm
Last updated: July 20, 2026
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Quick Answer

A counterclaim (Defendant's Claim) lets a defendant sue the plaintiff back in the same Ontario Small Claims case, up to the $50,000 limit. Filing costs a flat $108 ($228 for frequent claimants). If both sides prove part of their claims, the court sets the amounts off against each other and awards the net difference. A counterclaim does not replace your Defence, which is still due within 20 days of being served.

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$50,000 Jurisdiction

Ontario Small Claims Court handles claims — and counterclaims — up to $50,000. Amounts above that generally require abandoning the excess or moving to Superior Court.

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Filing a Counterclaim

A counterclaim is filed alongside your Defence, using Form 10A, generally within 20 days of being served with the Plaintiff's Claim.

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Related vs. Unrelated Claims

Counterclaims arising from the same transaction are most straightforward. Unrelated counterclaims may face procedural objections from the plaintiff.

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Don't Miss Your Deadline

Missing the deadline to file a Defence and Counterclaim can mean losing the right to counterclaim — and risking default judgment against you.

Counterclaims — Common Questions

What is a counterclaim in Small Claims Court?

A counterclaim (Defendant’s Claim) is a claim the defendant files back against the plaintiff in the same case — for example, if you are sued but the other side actually owes you money. It is generally filed within 20 days of delivering your defence.

Can a counterclaim be larger than the original claim?

Yes. A defendant can counterclaim for more than the plaintiff is seeking, up to the $50,000 Small Claims limit. If your counterclaim exceeds $50,000, you may need to proceed in the Superior Court instead.

How much does it cost to file a counterclaim?

Filing a Defendant’s Claim (counterclaim) costs a flat $108 for most filers ($228 for frequent claimants). Like the original claim, the fee does not scale with the amount claimed.

What happens if my counterclaim is larger than the plaintiff’s claim?

If both sides succeed, the court generally nets the two amounts against each other. If your counterclaim is larger and is proven, you can obtain judgment for the difference in your favour, up to the $50,000 Small Claims limit. This calculator estimates that net position from the figures you enter.

Do I still need to file a Defence if I file a counterclaim?

Yes. A counterclaim does not replace your Defence. You generally must deliver a Defence to the plaintiff’s claim within 20 days of being served, and separately file your Defendant’s Claim if you are also seeking money from the other side.

Can I counterclaim against someone who is not the plaintiff?

Yes. A Defendant’s Claim can be brought against the plaintiff and, in many cases, against another person you say is responsible — even someone not already in the lawsuit — which brings that person into the same case.

What is the deadline to file a counterclaim in Ontario?

A Defendant’s Claim is generally filed within 20 days after you file your Defence, and often at the same time. Filing promptly keeps everything in one proceeding; filing late can require the court’s permission or be dealt with separately.

What does “set-off” mean?

Set-off is the netting of the two claims against each other. If the plaintiff proves $8,000 and you prove a $5,000 counterclaim, the court can order the $3,000 net difference rather than two separate payments. This calculator shows that net figure.

Can I counterclaim for something unrelated to the plaintiff’s claim?

Often yes. A Defendant’s Claim can include related claims arising from the same events and, in many cases, other money the plaintiff owes you, as long as it is within the Small Claims Court’s jurisdiction and monetary limit.

What if my counterclaim is worth more than $50,000?

Small Claims Court can only award up to $50,000 (plus interest and costs). If your counterclaim genuinely exceeds that, you either give up the excess to stay in Small Claims Court or consider having the matter dealt with in the Superior Court.

Are the original claim and the counterclaim heard together?

Yes. The Defendant’s Claim is normally heard at the same time as the Plaintiff’s Claim, before the same judge, so all the related issues are decided together and the amounts can be set off.

What happens if both the claim and counterclaim partly succeed?

The court determines the amount each side proves, then sets them off. Whoever is owed the larger amount receives judgment for the net difference. Costs are decided separately and can go either way depending on the result.

Can filing a counterclaim ever backfire?

It can. A genuine counterclaim strengthens your position, but a weak or purely tactical one can hurt your credibility and expose you to a costs award. A counterclaim should be based on a real, provable entitlement.

Do I need a lawyer or paralegal to file a counterclaim?

You are allowed to file and argue a Defendant’s Claim yourself. For larger or more complex counterclaims — especially where a third party or set-off is involved — a lawyer or licensed paralegal can improve how the claim is framed and presented. We offer a free consultation.

Is this calculator’s result legal advice?

No. It provides a general estimate of the net amount in dispute based on the figures you enter. It is not legal advice, and the actual outcome depends on the evidence and the court’s findings. For advice on your specific case, speak with a lawyer or licensed paralegal.

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