Small Claims Court

Can you sue back if someone takes you to Small Claims Court?

Last updated October 7, 2026.

Yes. In Ontario Small Claims Court, a defendant can sue back with a Defendant's Claim (Form 10A) against the plaintiff, against another person connected to the dispute, or against both. It can be issued within 20 days after you file your Defence, or later with the court's permission, the filing fee is $108, and it is normally tried together with the plaintiff's claim. The same $50,000 limit applies.

Ontario's own pages also call this a "counterclaim." It turns a one-sided lawsuit into a single case where a judge can hear both sides' claims at once. This guide covers who you can claim against, the deadlines, the limits, and what happens next. For how Carson Frankum, a licensed paralegal in Hamilton, helps defendants respond to a claim, see our page on Small Claims Court help for plaintiffs and defendants.

How does a Defendant's Claim work, step by step?

The steps come from Rule 10 of the current Rules of the Small Claims Court (O. Reg. 258/98, as amended in 2025) and Ontario's guides to replying to and making a claim.

Deal with your Defence first. A Defendant's Claim does not replace a Defence. You still have 20 days after being served with the Plaintiff's Claim to serve and file a Defence (rule 9.01). Our guide on what to do after being served with a Plaintiff's Claim explains how to count those days. Ontario's guide suggests saying in your Defence that you are making a claim of your own.
Decide who you are claiming against. Rule 10.01(1) allows a claim against the plaintiff; against any other person, if the claim arises out of the transaction or occurrence the plaintiff relies on or is related to the plaintiff's claim; or against the plaintiff and another person together.
Complete Form 10A. The claim must name the parties, describe the claim "in concise non-technical language with a reasonable amount of detail," including the date, place and nature of what happened, state the amount and the relief you want, give an address where each person can be served, and show the court file number of the plaintiff's claim (rule 10.01(4)). Attach any document the claim is based on, or say why it is not attached.
File it at the same court office. A Defendant's Claim is filed where the plaintiff's claim was filed, with the $108 fee. It may be issued within 20 days after the day your Defence is filed, or later but before trial or default judgment with the court's permission (rule 10.01(2)). Outside the Toronto region you can file online through Small Claims Court Submissions Online, but not for a deadline three business days or less away. The clerk issues it with the same court file number as the plaintiff's claim (rule 10.01(6)).
Serve it properly. Unlike a Defence, a Defendant's Claim cannot simply be emailed. It must be served on every person it is made against personally or by an alternative to personal service (rules 10.02 and 8.01(1)), and rule 10.05(1) applies the usual six-month window for serving a claim (rule 8.01(2)). Complete an Affidavit of Service (Form 8A) for each person served.
Wait for their answer. Each person you claim against has 20 days after service to serve and file a Defence (rule 10.03). If someone does not, you can ask the clerk to note them in default, but judgment against them can be obtained only at trial or on motion, not signed by the clerk (rules 10.05(2) and 11.04). Our guide on default judgment in Small Claims Court explains noting in default.
Prepare for one settlement conference and one trial. A settlement conference is held in every defended action within 90 days after the first defence is filed (rules 13.01(1) and (3)), and a Defendant's Claim is tried and disposed of at the trial of the action unless the court orders otherwise (rule 10.04(1)).

Defendant's Claim deadlines in Ontario Small Claims Court
Step	Deadline	Rule
Serve and file your Defence to the plaintiff's claim	20 days after you are served with the claim	r. 9.01
Issue your Defendant's Claim	20 days after your Defence is filed; later only with the court's permission, before trial or default judgment	r. 10.01(2)
Serve your Defendant's Claim	Within six months after it is issued (the court can extend)	r. 8.01(2), 10.05(1)
Defence to your Defendant's Claim	20 days after service on that person	r. 10.03
Settlement conference	Within 90 days after the first defence is filed	r. 13.01(3)
If the plaintiff's action is dismissed for delay	Your Defendant's Claim is deemed dismissed 60 days after the dismissal order is served, unless the court orders otherwise in that time	r. 11.1.02

Who can you claim against, and when is a Defendant's Claim the wrong tool?

The rule covers two common situations. The first is that the plaintiff owes you something from the same dealings: the balance on a contract, a deposit never returned, or damage the plaintiff caused to your property. The second is that someone else is really to blame for the plaintiff's loss, such as a supplier, a subcontractor or a manufacturer. Ontario's guide gives the example of a roofer, sued over a leak, who claims against the shingle maker.

Is a Defendant's Claim the right route?
Your situation	Route	Rule or source
The plaintiff owes you money or property from the same dispute	Defendant's Claim against the plaintiff	r. 10.01(1)(a)
Someone else is responsible for all or part of the plaintiff's loss	Defendant's Claim against that person	r. 10.01(1)(b)
Both of the above	One Defendant's Claim against the plaintiff and the other person	r. 10.01(1)(c)
A claim against someone else with no connection to this dispute	A separate Plaintiff's Claim ($108, or $228 for a frequent claimant)	r. 10.01(1)(b); O. Reg. 332/16
What you are owed is more than $50,000	Claim up to $50,000 here and give up the rest, or sue in the Superior Court of Justice, where you would need a lawyer	O. Reg. 626/00, s. 1; r. 6.02; Ontario guidance
More than 20 days have passed since your Defence was filed	Motion for the court's permission, before trial or default judgment ($127 motion fee)	r. 10.01(2)(b)

A claim against a stranger to the dispute does not fit rule 10.01(1)(b), because the rule requires a link to the plaintiff's transaction or claim. You can still sue that person, but in a fresh action of your own, which may also have to be started in a different court location.

What changes the answer?

The size of your claim. The maximum amount of a claim in the Small Claims Court is $50,000 (O. Reg. 626/00, s. 1, in force since October 1, 2025), not counting interest and costs (Courts of Justice Act, s. 23(1)). You cannot divide one cause of action into pieces to fit under the cap (rule 6.02). Our guide on how much you can sue for explains the limit. Ontario says you can still file if you are willing to waive the amount over $50,000, a choice covered in our guide on waiving the amount over the limit.
Timing. After the 20 days, you need the court's permission, and only before trial or default judgment (rule 10.01(2)(b)). That means a motion, with a $127 fee. Our article on how to file a motion in Small Claims Court covers the form.
The limitation period. Most claims must be started within two years of the day the claim was discovered (Limitations Act, 2002, s. 4). For a claim against another alleged wrongdoer for contribution and indemnity, section 18 treats the day you were served with the plaintiff's claim as the day the act or omission took place, so the two-year clock is presumed to start then.
The court separates the claims. If a Defendant's Claim may unduly complicate or delay the trial, or cause undue prejudice to a party, the court can order separate trials or have it proceed as a separate action (rule 10.04(2)).
A third party wants to fight the main claim. If you say a third party is liable to you for all or part of what the plaintiff claims, that third party can contest your liability to the plaintiff at trial, but only if it has filed a Defence (rule 10.04(3)).
Someone does not attend the trial. If the defendant is absent, the judge can strike the Defence and dismiss the Defendant's Claim; if the plaintiff is absent, the judge can dismiss the action and let the defendant prove the Defendant's Claim (rule 17.01(2)). Our guide on what happens at a Small Claims trial explains the day.
You have been noted in default. A defendant noted in default cannot take any step, other than a motion to set aside, without the court's permission or the plaintiff's consent (rule 11.05(1)), and that includes filing a Defendant's Claim.

A worked example

For example, imagine a Hamilton caterer named Marcus whom an event venue sues for $7,200, saying his staff damaged its commercial kitchen. Marcus says two things. First, the venue never paid his last invoice of $3,100 for a wedding he catered there. Second, the damage was caused by a fryer that an appliance repair company had serviced the week before, and he has the repair company's work order.

Marcus serves and files his Defence within 20 days of being served, disputing the claim with numbered reasons and attaching the work order. Within 20 days after filing it, he files one Defendant's Claim, paying $108: it claims the $3,100 from the venue (rule 10.01(1)(a)) and claims against the repair company for any amount Marcus is found to owe the venue (rule 10.01(1)(b)). Both are corporations, so he serves each one by leaving a copy with a person who appears to be in control or management at its place of business (rule 8.02(c)). The repair company files a Defence within 20 days, which keeps its right to contest Marcus's liability to the venue at trial. All three parties then attend one settlement conference, where the claims can be settled together. The example shows how the steps fit together, not how the case would end.

Common mistakes people make

Putting the counterclaim only in the Defence. A Defence answers the plaintiff's claim; it does not make a claim of your own. Ontario's guidance is to mention it in the Defence and also file Form 10A.
Mixing up the two 20-day clocks. The Defence is due 20 days after you are served; the Defendant's Claim is due 20 days after your Defence is filed. Missing the second means a motion and a $127 fee.
Emailing the Defendant's Claim. A Defence can be served by email, but a Defendant's Claim must be served personally or by an alternative to personal service (rules 8.01(1) and 10.02).
Bringing in an unconnected party. A claim against someone with no link to the plaintiff's transaction or claim falls outside rule 10.01(1)(b).
Ignoring the cost risk. Costs other than disbursements are generally capped at 15 per cent of the amount claimed (Courts of Justice Act, s. 29), and that applies to your claim as well. A written offer to settle can change the costs picture; see our guide on how an offer to settle affects costs.
Assuming your claim survives on its own. If the plaintiff lets the main action be dismissed for delay, your Defendant's Claim is deemed dismissed 60 days after that order is served unless the court orders otherwise (rule 11.1.02).

What to do this week

Work out your Defence deadline from the date of service, and diarize a second deadline 20 days after the day you plan to file your Defence.
List what the plaintiff owes you from the same dealings, and anyone else who may be responsible for the plaintiff's loss.
Gather contracts, invoices, work orders, payment records and photos for both your Defence and your claim.
Check that your claim is within the $50,000 limit and was discovered within the last two years.
Complete Form 10A with the plaintiff's court file number and an address for service for each person you are claiming against.
File it at the court office named on the plaintiff's claim with the $108 fee, or apply for a fee waiver if you qualify.
Arrange personal or alternative service on each person, and complete an Affidavit of Service for each.

Frequently asked questions

Is a Defendant's Claim the same thing as a counterclaim?

Yes, in plain terms. Ontario's "being sued" page uses both names for a new claim of your own against the plaintiff or another person. The Rules call it a Defendant's Claim, and the person who makes it is described in Ontario's guide as a "plaintiff by defendant's claim."

How much does it cost to file?

The court fee for a Defendant's Claim is $108 under O. Reg. 332/16. The regulation's frequent claimant rate applies to claims, and its definition of "claim" leaves out a Defendant's Claim, so the fee is the same for everyone. Our guide to Small Claims Court fees lists the other charges, and people with low household income can apply for a fee waiver.

Will the judge decide both claims together?

Usually. Rule 10.04(1) says a Defendant's Claim is tried and disposed of at the trial of the action unless the court orders otherwise. The court can split them if keeping them together would unduly complicate or delay the trial.

Can I add someone who was not named by the plaintiff?

Yes, if your claim against them arises out of the same transaction or occurrence as the plaintiff's claim, or is related to it (rule 10.01(1)(b)). They become a party and must be served personally or by an alternative to personal service.

What happens if the person I sue back ignores my claim?

You can have them noted in default after 20 days, using a Request to Clerk (Form 9B) and proof of service. Unlike a plaintiff with a fixed debt, you cannot get a clerk's signature on a default judgment; judgment against them comes at trial or on a motion (rule 11.04).

Can I ask for more than the plaintiff is claiming from me?

Yes. A Defendant's Claim is treated as a claim in its own right (rule 10.05(1)), so its amount depends on what you can prove, up to the $50,000 limit. A larger counterclaim also raises the costs at stake for both sides.

Can a licensed paralegal prepare and argue my Defendant's Claim?

Yes. A paralegal licensed by the Law Society of Ontario can prepare the documents and represent you in Small Claims Court. If the case is in Hamilton, our page on the Small Claims Court in Hamilton covers the local office.

Sources

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This page gives general information about Ontario law, not legal advice for your situation. Cheddar Paralegal PC is a paralegal firm licensed by the Law Society of Ontario; licensed paralegals can help only with matters the Law Society allows paralegals to handle.