How to file a notice of objection in Canada

Step 1 — Confirm your deadline

Income tax: individuals get the later of one year after the filing-due date and 90 days after the notice was sent; corporations and other trusts get 90 days after sending (ITA s.165(1)). GST/HST: 90 days after the notice is sent (ETA s.301(1.1)). Day 0 is the date printed on the notice (ITA s.244(14)). Check your deadline free →

Step 2 — Write a valid objection

A valid objection must:

• clearly explain what is being objected to and why — which assessment, which lines, which amounts;
• set out the reasons and ALL relevant facts — organised issue by issue, with the relief sought for each;
• include supporting documentation — the evidence behind your facts.

Best practice is a per-issue structure: describe each issue, specify the relief sought for each, and give the facts and reasons for each. (Large corporations are required by statute to do it this way — ITA s.165(1.1) — and "specified persons" face a similar requirement for GST/HST at ETA s.301(1.2). Everyone else should do it anyway.)

For income tax you may file on Form T400A or in a signed letter. For GST/HST you must use the prescribed Form GST159 — not a plain letter, and not T400A. See the GST/HST guide →

Step 3 — File with the Appeals Intake Centre

Send your objection to:

• By mail to the address above.
• By fax (income tax): 705-670-6649 or 1-866-443-4955. No fax number is documented for GST/HST — mail those.
• Online: "Register my formal dispute" in My Account for Individuals, or "File a formal dispute" in My Business Account; representatives use Represent a Client.

Verify the address, fax numbers, and online options on canada.ca before filing — details change, and the CRA's current instructions control.

Step 4 — Know what happens next

• The CRA validates your objection and assigns an appeals officer, who reviews it independently of the original assessment.
• Resolution times: CRA service standards are 180 days (low-complexity, 80% target) and 365 days (medium-complexity). Actual June 2026 averages: 127 days (low), 389 days (medium), 690+ days (high-complexity, 2–3% of workload).
• Interest keeps accruing on any amount owing during the dispute — paying now reduces interest even if you later win.
• Collections are generally suspended on the disputed amount until 90 days after the Minister's decision notice is sent (ITA s.225.1(2)), with exceptions including source deductions.

Step 5 — If you disagree with the decision

If the Minister's decision doesn't resolve things in your favour, the next step is generally an appeal to the Tax Court of Canada — which has its own strict deadline. That's beyond a DIY packet; get professional help at that stage.