CRA Notice of Objection: How to File and the 90-Day Deadline
A Notice of Objection is the formal way to dispute a CRA assessment or reassessment. The deadline is 90 days from the date on the notice, filed online through CRA My Account or via Form T400A. An appeals officer outside the original audit team reviews. If still disputing after the decision, you can appeal to the Tax Court of Canada within 90 days.
A Notice of Objection is the formal way to dispute a CRA assessment or reassessment. The deadline is 90 days from the date on the notice, and missing it can permanently lock in the assessed amount. You file using Form T400A by mail, the equivalent online form in CRA My Account, or for GST/HST disputes Form GST159. The objection is reviewed by an appeals officer outside the original audit team, and the file can be confirmed, varied, or vacated. If you still disagree after the appeals decision, you have 90 days to appeal to the Tax Court of Canada.
The 90-day deadline
Action
Time limit
File Notice of Objection
90 days from the date on the (re)assessment notice
Apply for an extension if 90 days passed
Up to 1 year past the original 90-day deadline; CRA discretion
Appeal to Tax Court of Canada after an objection
90 days from the appeals decision, or 90 days after objection if no decision in 180 days
Appeal to Tax Court directly without an objection
Not permitted in most cases; objection is a precondition
How to file
Method
Detail
CRA My Account / My Business Account
Online “Register a formal dispute” service. Fastest method.
Form T400A (paper)
Mail to the appropriate Tax Services Office. Include reasons, facts, and supporting documents.
Form GST159
Used for GST/HST objections. Same 90-day rule.
Letter
Allowed if it includes the same content as Form T400A: name, SIN/BN, year(s) under dispute, reasons, facts, and signature.
What to include
Identification: name, social insurance number or business number, address, contact information.
The notice you are objecting to: date, tax year(s), and reference number.
The specific items you are disputing.
The facts as you understand them, including dates and amounts.
The reasons why CRA’s adjustment is wrong.
Any supporting documents (receipts, contracts, correspondence).
Authorization for a representative if applicable (Form AUT-01 attached or filed separately).
What happens after you file
Stage
What CRA does
Typical timing
Acknowledgment
CRA confirms receipt and assigns an appeals officer.
2-8 weeks
Review
Appeals officer reviews the file independent of the original auditor. May request more documents or a phone call.
4 to 12 months for individual T1 objections; longer for corporate or complex files
Decision letter
CRA confirms (no change), varies (partial agreement), or vacates (full agreement) the assessment.
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Tax Court appeal
If still disputing, file a Notice of Appeal in Tax Court of Canada within 90 days of the decision.
1-3 years through the General Procedure; 6-18 months through the Informal Procedure (under $25,000 federal tax per year per person)
Worked example: T1 medical expense disallowed
A taxpayer claims $4,500 of medical expenses for a parent. CRA reassesses to disallow $2,800, citing missing receipts. The reassessment increases tax owing by $420 federal plus $230 provincial.
Day 0: Notice of reassessment issued November 12, 2025.
Day 1-90: Taxpayer has until February 10, 2026 to file an objection.
Day 30: Taxpayer logs into CRA My Account, files an objection through “Register a formal dispute,” uploads receipts and prescription documentation that supports the disallowed expenses.
Day 90: CRA acknowledges receipt, assigns appeals officer.
Month 6-9: Appeals officer requests one additional document; resolves in writing without a meeting.
Month 10: CRA issues decision letter vacating the disallowance. The original $4,500 claim is restored.
Common mistakes
Missing the 90-day deadline. Late objections require an extension application within 12 months and CRA may refuse.
Filing without supporting documents. The objection should resolve through an appeals officer review; thin filings risk a confirmation.
Stopping payment during the objection. Interest accrues throughout. Partial payment of the disputed amount is normal.
Using Form T400A to dispute non-tax matters. Penalty assessments can be disputed; some collection actions cannot be objected to.
Filing for a year where you should have used Voluntary Disclosures Program. Once CRA contacts you about a year, VDP relief is no longer available for that year.
90 days from the date on the (re)assessment notice. Late filings up to one year past the deadline may be accepted with an extension request, at CRA discretion.
How do I file a Notice of Objection?
Online through CRA My Account using "Register a formal dispute," by mail using Form T400A, or by letter that contains the same information.
Do I need a lawyer to file?
No. Most individual objections are filed by the taxpayer. A representative can be authorized using Form AUT-01.
What happens after I file?
An appeals officer outside the original audit team reviews the file and issues a decision letter that confirms, varies, or vacates the assessment. Average resolution is 4 to 12 months for individual T1 objections.
Can I appeal to Tax Court without filing an objection first?
Generally no. The Notice of Objection is a precondition. Direct appeals are allowed only in narrow circumstances such as where CRA has not decided an objection within 180 days.
Does interest stop while my objection is being reviewed?
No. Interest continues to accrue at the prescribed rate (9 percent in Q2 2026). Many taxpayers pay the disputed balance during the review and receive interest if they win.
What is the difference between General and Informal Procedure at Tax Court?
Informal Procedure applies when federal tax in dispute is $25,000 or less per year (or $50,000 in losses), with simpler rules and no requirement for a lawyer. General Procedure applies above those thresholds with more formal court rules.