Third-Party Claim in the Alberta Court of Justice: When Someone Else Is Responsible

What a Third-Party Claim Does

Sometimes you're sued for something that's partly or entirely someone else's fault. A homeowner sues you for defective renovation work, but the problem was actually caused by the subcontractor who did the plumbing. A customer sues your business over a product defect, but the manufacturer supplied the faulty component.

A third-party claim lets you bring that other person or business into the existing court action. Instead of dealing with the plaintiff's claim alone and then having to start a separate lawsuit against the real responsible party, you resolve everything in one proceeding.

In the Alberta Court of Justice, this is filed in addition to your Dispute Note. The third party gets brought into the case and must respond to your claim against them, just as you're responding to the plaintiff's claim against you.

How It Works

Filing: You file a Third-Party Claim in addition to your Dispute Note. The filing fee is $50 — separate from your Dispute Note fee.

Service: This is where it differs from a standard Dispute Note. When you file a regular Dispute Note, the court clerk mails copies to the other parties. With a third-party claim, you are responsible for serving the Third-Party Defendant, the plaintiff, and the other defendants within 30 days after filing your Dispute Note. You must deliver:

• A filed copy of your Dispute Note and Third-Party Claim
• A blank Dispute Note to a Third-Party Claim form (so the third party can respond)
• A copy of the original Civil Claim (so they know what the underlying case is about)

Proof of service: File an Affidavit of Service of Commencement Documents for the Third-Party Defendant and an Affidavit of Service of Non-Commencement Documents for the plaintiff and existing defendants, confirming when and how service was completed.

The third party's response deadline: The newly added party gets 20 calendar days (if served in Alberta) or 30 calendar days (if served outside Alberta) to file a Dispute Note to a Third-Party Claim.

Third-Party Claim vs. Counterclaim

These are different tools for different situations:

A counterclaim is your own claim against the plaintiff — the person who sued you. The contractor sued you for the invoice balance, but you're claiming money from them for the defective work.

A third-party claim brings in someone new — a party who isn't currently part of the case but who you say is responsible for some or all of what the plaintiff is claiming.

You can file both: a Dispute Note that contests the plaintiff's claim, includes a counterclaim against the plaintiff, and adds a third-party claim against someone else. The fees stack — $50 for the Dispute Note, the applicable counterclaim fee ($100 or $150), and $50 for the third-party claim.

When It Makes Sense

Third-party claims are most useful when the chain of responsibility is clear:

• Subcontractor liability — you hired a subcontractor whose work caused the damage the plaintiff is suing you for
• Product defects — you sold a product manufactured by someone else and the defect came from the manufacturing, not your handling
• Joint activity — you and another person were both involved in the situation and you believe the other person bears some or all of the responsibility
• Insurance or indemnity — someone contractually agreed to indemnify you against exactly this type of claim

The claim is for a person or business you say is wholly or partly responsible for the damages the plaintiff claims. It is not a way to bring in an unrelated dispute.

Practical Considerations

Adding a third party complicates the proceedings. The court now has three (or more) parties, potentially conflicting accounts of what happened, and more evidence to review. Cases with third-party claims tend to take longer to resolve and are less likely to settle at mediation.

Before filing, consider whether the third party is genuinely responsible and whether the amount at stake justifies the additional complexity. For a $3,000 claim where you think the third party is 30% responsible, the $50 filing fee, the service costs, and the extended timeline may not be worth recovering $900.

Also consider whether you can resolve the underlying claim with the plaintiff first and then pursue the third party separately if needed. This keeps the original case simpler and gives you more control over both proceedings.

The Service Requirement Matters

Unlike your own Dispute Note (where the clerk mails copies to the plaintiff), you must personally arrange service on the third party. If service isn't completed properly, the third party can challenge it, which delays the entire case.

Use a service method permitted for a Civil Claim. Keep careful records of when and how service was done — you'll need them for the Affidavit of Service.

The Alberta Civil Claim Response Guide covers the third-party claim process alongside the other Dispute Note options, including the service requirements and the additional forms you'll need to file.

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