Amending a Plaintiff's Claim in Ontario Small Claims Court

Filing a Plaintiff's Claim is rarely the last word on the details of a dispute. New facts surface, a defendant's correct legal name comes to light, or the true amount owed turns out to be different from your first estimate. Ontario's Small Claims Court allows plaintiffs to amend a claim that has already been filed, but how easily depends on timing and what exactly you want to change.

This guide walks through when amendments are straightforward, when you need the court's permission, and how to actually make the change once you have filed a Plaintiff's Claim.

Why Plaintiffs Amend a Claim

Typical reasons to amend include:

• Correcting a defendant's name — a misspelling or the wrong corporate name
• Adding a party you didn't realize was involved when you first filed
• Removing a party who turns out not to be responsible
• Increasing or decreasing the amount claimed as new information comes in
• Adding or clarifying facts that support the claim

None of these are unusual. Courts expect that a claim drafted early in a dispute may need refinement as the picture becomes clearer.

Amending Before vs. After the Defendant Responds

The general principle in Ontario civil and Small Claims procedure is that amendments are easier before the other side has engaged with the claim, and require more formality — often the court's permission — once a defendant has filed a defence and is relying on the claim as originally framed.

• Before service, or before a defence is filed: amendments are typically more freely available, since no one has yet responded to the claim as it stands.
• After a defence is filed: you will generally need to ask the court for permission to amend, and the other side gets a chance to weigh in, particularly if the amendment would prejudice their ability to respond.

Adding or Removing a Party

Adding a new defendant partway through a case raises a limitation period question: if the basic limitation period has already run by the time you try to add someone, the court may not allow it, unless the situation fits a recognized exception — for example, correcting a genuine misnomer of a party you always intended to sue, as opposed to adding someone entirely new. This is exactly why identifying every potentially responsible party, and their correct legal name, before you first file matters so much.

Removing a party is generally more straightforward, since dropping someone from a claim doesn't raise the same limitation concerns.

Changing the Amount Claimed

You can generally amend the amount you are claiming as your understanding of your losses develops. Two limits matter here:

• The amended amount must still fall within Small Claims Court's monetary jurisdiction — $50,000, exclusive of costs and interest, as of mid-2026, but verify the current limit before relying on it. If your revised claim exceeds that, the matter may need to proceed in a different court instead.
• Increasing the claim substantially after a defendant has already responded based on the original amount may require the court's permission, particularly close to a scheduled hearing.

How to Actually File an Amendment

1. Identify exactly what needs to change — the parties, the amount, or the underlying facts.
2. Check the stage of the proceeding — whether a defence has been filed changes whether you need consent or the court's permission.
3. Prepare the amended claim, reflecting only the changes needed, following the court's required format.
4. Serve the amended version on all parties, including any newly added defendant.
5. File proof of service and, where required, bring a motion for the court's permission to amend.

Frequently asked questions