How to file a notice of objection with the CRA

An objection is a formal review of an assessment by a separate part of the CRA. It is a real remedy, and its deadline is what people most often miss.

Talk to the CRA first

The CRA suggests calling or writing first; many disputes end there. A missed item on a return calls for an adjustment request, which is faster. Object when facts or law were applied wrongly.

The deadline for a notice of objection

Note what the clock runs from: the date on the notice, not the date you opened the envelope or noticed the problem. That single fact is why reading your notice of assessment properly, and recording its date, matters.

Missing the deadline

You can seek an extension when filing, as soon as possible and no later than one year after the date the objection was due. Show you could not object or intended to, that granting it is fair, and that you applied promptly. If refused, apply to the Tax Court of Canada within 90 days of the refusal.

How to file

• Online through My Account, My Business Account, or Represent a Client, by selecting “Register my formal dispute.” The CRA states that filing through a secure portal gets the objection received and assigned to an appeals officer sooner, and you get a case number automatically.
• By mail or fax using Form T400A, Objection — Income Tax Act, sent to the Chief of Appeals at your Appeals Intake Centre.
• By signed letter setting out the facts and reasons, sent the same way.

What to include

Include your name, address, daytime phone, notice date, tax year, SIN or business number, facts and reasons, supporting documents and any representative. Sign and date it; an authorized officer signs for a corporation or trust. Use one objection per assessment.

What happens next

You get a case number; an appeals officer reviews it and usually contacts you. You may request documents such as the auditor’s report and working papers. The outcome is a reassessment or a confirmation.

To disagree further, appeal to the Tax Court of Canada within 90 days of the decision, or if no decision comes within 90 days of filing.

What about the money

Objecting usually pauses collection of the disputed amount until 90 days after the decision, except for withheld and remittable amounts. Large corporations pay 50% up front. Interest keeps running, so paying cuts interest without harming the objection. If you cannot pay, see what happens in CRA collections.

The bottom line

Call first, note the notice date, and file on time — 90 days for a corporation, the later of two dates for an individual — with facts, reasons and documents. If a review started it, see CRA information requests and audit triggers. We represent clients through our tax services.

This article is general information for Canadian business owners and is current as of July 2026. It is not tax, legal or accounting advice, and it does not create a client relationship. Tax rules change and your situation is unique, so please speak with a CPA before acting on anything here.