Small Claims
Counterclaim Calculator.
Been served with a Small Claims claim — but the plaintiff owes you too? This tool sets your counterclaim off against their claim to show your real net position, whether it fits the $50,000 limit, what the Defendant's Claim (Form 10A) costs to file, and the 20-day deadline. Updated for 2026.
· Reviewed by Jonathan Kleiman, J.D.
Ontario Bar
Rules of Court
200+ reviews
consultation
Should you file a counterclaim in Small Claims Court?
File a counterclaim when the plaintiff genuinely owes you money you can prove — because a Defendant's Claim is set off against their claim, it can shrink what you owe or, if it's larger, flip the case so the plaintiff owes you. Skip it when you can't prove a real claim, since a counterclaim brought only for leverage adds a filing fee and its own costs risk.
Enter what you're being sued for and what the plaintiff owes you, and the calculator below shows your net position, whether the counterclaim fits the $50,000 Small Claims limit, what it costs to file, and the deadline to get it in.
Counterclaim Calculator
You've been sued — but do they owe you? See your net position, what it costs to file, and your deadline. Fields marked * are required.
What is a counterclaim in Small Claims Court?
A counterclaim is a claim you bring back against the person suing you, made on a Defendant's Claim (Form 10A) under Rule 10 of the Rules of the Small Claims Court. Being served with a Plaintiff's Claim doesn't only put you on defence — if the plaintiff owes you money, whether on the same deal or an unrelated one, you can sue them right back in the same case. The two claims are then heard together and, to the extent both are proven, set off against each other.
How does a set-off work?
A set-off nets the two claims against each other, so only the difference actually changes hands. Say the plaintiff sues you for $15,000 and you counterclaim for $22,000. If a judge accepts both, the set-off leaves the plaintiff owing you $7,000 — the counterclaim didn't just defend the case, it flipped it. If your counterclaim were smaller — say $6,000 — you'd owe $9,000 instead of $15,000. Either way the counterclaim works only to the extent you actually prove it; winning the defence and winning the counterclaim are two separate battles.
Can a counterclaim be more than the claim against me?
Yes — a counterclaim can be larger than the plaintiff's claim, but it's still capped at the $50,000 Small Claims Court limit. A bigger counterclaim is exactly how a defendant turns the tables. But if what you're owed tops $50,000, you have to choose: cap the Defendant's Claim at $50,000 and give up the excess, or take the fight to the Superior Court of Justice, where there's no ceiling but the process costs more. The calculator flags the moment your number crosses the limit.
What does a counterclaim cost, and when is it due?
The Defendant's Claim (Form 10A) costs $108 to file, and it must be issued within 20 days of filing your Defence. In practice the Defence and the counterclaim travel together — the Defence is due within 20 days of being served, so build both at once and file them as a pair. Miss the Defence deadline and you can be noted in default before you ever get your counterclaim in. If you're defending as well, add the $77 Defence fee; the Filing Fee Calculator prices every step, and win or lose, the successful party usually recovers its filing fees.
Served, and the clock is running?
Free 30-minute consultation. Bring the claim; leave knowing whether you have a counterclaim worth filing — and by when.
Is it worth filing a counterclaim?
A counterclaim is worth filing when you have a genuine claim you can prove and the amount is large enough to matter; it's not worth it when it's thin or purely tactical. A real counterclaim can erase your exposure or reverse it, and it lets you resolve both disputes in one case instead of starting a second lawsuit later. But a weak Defendant's Claim filed just to gain leverage costs $108, invites its own costs award if it fails, and can distract from the defence that actually matters. Bring your best claim, not every grievance. Once you have a sense of the numbers, refine the pieces with the Small Claims Court Calculator for the value of your own claim, the Limitation Period Calculator to confirm you're still in time, and the Settle or Go to Court Calculator once an offer is on the table.
Counterclaim FAQ
What is a counterclaim in Ontario Small Claims Court?
A counterclaim is a claim you bring back against the person suing you. In Ontario Small Claims Court it's made on a Defendant's Claim (Form 10A) under Rule 10 of the Rules of the Small Claims Court. If both claims are proven at trial they're set off against each other, so the counterclaim can reduce what you owe — or, if it's larger, leave the plaintiff owing you.
What is the deadline to file a Defendant's Claim (counterclaim)?
Under Rule 10.01(2), a Defendant's Claim must be issued within 20 days after the day you file your Defence. Because the Defence is itself due within 20 days of being served with the Plaintiff's Claim, most defendants file the Defence and the counterclaim together. The court can allow a later counterclaim, but only with leave. Check your Defence date with the Defence Deadline Calculator.
How does a set-off work with a counterclaim?
A set-off nets the two claims against each other. If the plaintiff proves a $15,000 claim and you prove a $22,000 counterclaim, the set-off leaves the plaintiff owing you $7,000. If your counterclaim is smaller, it reduces what you owe rather than eliminating it. The set-off only applies to the extent both claims are actually proven at trial.
Can a counterclaim be more than the $50,000 Small Claims Court limit?
No. A Defendant's Claim is subject to the same $50,000 monetary limit as any other Small Claims Court claim. If what the plaintiff owes you is more than $50,000, you can cap the counterclaim at $50,000 and give up the excess, or pursue it in the Superior Court of Justice instead. Which route is right depends on the amounts and the cost of each forum.
How much does it cost to file a counterclaim?
The court filing fee for a Defendant's Claim (Form 10A) is $108. If you're also filing a Defence, add the $77 Defence fee. The successful party can normally recover its filing fees from the losing side, along with reasonable disbursements and, if represented, up to 15% of the amount claimed in representation fees. See the Filing Fee Calculator for every step.
Does a counterclaim have to be related to the plaintiff's claim?
No. A Defendant's Claim can raise any claim you have against the plaintiff, related or not — for example, being sued over one invoice while you're owed on another. It can also be brought against people other than the plaintiff, which makes it a crossclaim or third-party claim under different parts of Rule 10. A counterclaim still has to be a real claim you can prove, and it has its own limitation deadline.
Been sued, and think they owe you?
Jonathan Kleiman defends Small Claims Court cases across Toronto and Ontario — and files the counterclaims that turn a defence into an offence. Get a straight read on whether your Defendant's Claim is worth bringing, and the deadline to get it in.
- Free 30-minute consultation
- Flat-fee and block-fee pricing — no surprises
- Defence and counterclaim (Form 10A) prepared together
- Deadline and default-risk triage
- Available evenings and weekends
- Serving Toronto and all of Ontario
Request a free consultation
Describe the claim against you and what you're owed, and Jonathan will contact you — usually the same day. If you ran the calculator, your estimate is attached automatically.
About this tool — please read
This page provides general legal information and a simplified decision model for educational purposes only. It is not legal advice, does not account for the specific facts, evidence, or law that govern your dispute, and creates no lawyer–client relationship. The set-off figures assume each claim is proven in full at trial; in reality the plaintiff's claim and your counterclaim are decided separately on their own evidence, and either can succeed or fail independently. The tool does not assess whether your counterclaim is legally sound, whether it is within time under the Limitations Act, 2002, or whether it should be brought against additional parties. Filing fees and the $50,000 monetary limit are current as of 2026 but can change. Consult a qualified Ontario lawyer or paralegal about your specific situation before you file a Defence or a Defendant's Claim.
A claim against you can become a claim of your own.
Book a free 30-minute consultation with Jonathan. Bring the papers you were served, and leave knowing whether you have a counterclaim worth filing — and the deadline to file it.