Tax Guide/CRA notices
Filing a notice of objection
Updated November 4, 2026
A notice of objection is the formal way to dispute an assessment. The CRA's Appeals branch reviews it separately from the people who made the original decision.
Deadline for individuals
Use the later of:
- 90 days after the date on the notice
- One year after the filing due date for that return
Corporations generally have only 90 days. Do not leave this to the last minute. The deadline can only be extended in limited cases.
How to file
Use My Account or Form T400A, and explain the facts and reasons. Collection of income tax in dispute is generally on hold during an objection, but interest continues. If you lose, you can often appeal to the Tax Court of Canada.