Fill Out CRA Form T400A Online
Notice of Objection - Income Tax Act
Canada Revenue Agency
Formally objects to an income tax assessment or determination issued by the CRA.
Reviewed July 2026
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CRA Form T400A, Notice of Objection - Income Tax Act, is the formal way to dispute an assessment, reassessment, or determination issued by the Canada Revenue Agency. Filing an objection moves your file to the CRA's Appeals Branch, where an appeals officer who was not involved in the original decision reviews your position.
You can complete Form T400A in the Universal PDF editor, set out the facts and reasons for your objection in the form's fields, and download the finished PDF to send to the CRA. A clear, well-organized objection gives the appeals officer everything needed to review your case.
What is Form T400A used for
An objection is the required first step in the formal dispute process under the Income Tax Act. It preserves your rights: if you disagree with the appeals decision later, you can appeal to the Tax Court of Canada, but only if a valid objection was filed on time.
The form asks you to identify the assessment or determination in dispute and to explain the relevant facts and the reasons you believe the CRA's position is wrong. Supporting documents, such as receipts or calculations, strengthen the objection and can be included with it.
Who files Form T400A and by when
Any taxpayer who disagrees with an income tax assessment, reassessment, or certain determinations can object: individuals, corporations, trusts, and their authorized representatives. Before objecting, it is often worth checking whether a simple adjustment request would resolve the issue, since objections are for genuine disputes rather than routine corrections.
Deadlines are strict. Individuals and graduated rate estates generally must object by the later of one year after the return's filing due date for the year and ninety days after the date on the notice of assessment. Other taxpayers, including corporations, generally have ninety days from the date of the notice. If you missed the deadline recently, you can apply for an extension within the period allowed by the Act, but extensions are not automatic.
How to fill out Form T400A
Set out your case completely; the appeals officer starts from what you provide:
- Identification: your name, address, social insurance number or business number, and daytime contact information.
- Assessment details: the taxation year, the date on the notice of assessment or reassessment, and what is being disputed.
- Facts and reasons: a plain statement of the relevant facts and why you disagree, issue by issue. Attach schedules or documents that support each point.
- Signature: sign and date the form, or have an authorized representative do so with the proper authorization on file.
Where to send it and what happens next
Send the objection to the address in the form instructions, or file an objection through the CRA's online services, which accomplishes the same thing without the paper form. The Appeals Branch will acknowledge the objection, may ask for more information, and will either confirm, vary, or vacate the assessment.
Collection of amounts in dispute is generally paused for individuals while a valid objection is under review, although interest continues to accrue on any amount that remains payable in the end. If the amounts are significant or the issues are technical, consider getting advice from a tax professional before filing.
Frequently asked questions
Individuals and graduated rate estates generally have until the later of one year after the return's filing due date and ninety days after the date on the notice of assessment. Most other taxpayers have ninety days. Extensions can be requested within the time allowed by the Act, but they are discretionary.
For most individuals, the CRA generally holds off collecting the disputed income tax while the objection is in progress, but interest keeps accruing. Different rules apply to certain taxpayers and certain amounts, so verify how the rules apply to you.
No. You can file an objection through the CRA's online services or by writing to the Chief of Appeals with the same information. The T400A is the prescribed paper form and keeps everything in one structured document.
If you simply forgot a slip or a deduction, an adjustment request is usually faster. An objection is for genuine disagreements with the CRA's interpretation or findings. Filing an objection preserves your right to appeal to the Tax Court of Canada later.
The CRA issues a decision confirming or varying the assessment. If you still disagree, you can generally appeal to the Tax Court of Canada within ninety days of the decision.
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