Objecting to a Reassessment That Followed a CRA Audit in Canada

After a CRA audit, you may receive a proposal letter and then a notice of reassessment that changes your tax. It is natural to wonder whether the auditor's findings are the last word.

They are not necessarily. A formal objection asks the CRA to reconsider the reassessment. This article explains what an objection adds, the deadlines, and what to prepare. Every audit turns on its own facts, so consider legal or accounting advice.

This article covers Canadian federal tax law, which applies in every province.

What you can and cannot object to

You cannot object to an auditor's proposal letter or a statement of account. You can object to a notice of assessment, reassessment, determination or redetermination. So when an audit ends in a reassessment, that notice is what you object to.

A reassessment can be issued within the normal reassessment period, which is three years after the original notice of assessment, or four years for mutual fund trusts and corporations other than CCPCs. The Minister may reassess later for misrepresentation attributable to neglect, carelessness, wilful default or fraud, or where a prescribed waiver was filed in the normal period. A notice of reassessment starts new objection rights over the reassessed items.

An assessment is deemed valid and binding despite any error, defect or omission, subject to objection, appeal and reassessment. That is why a deadline matters: if you do nothing, the assessment stands.

What the objection process adds

An objection is a written notice setting out your reasons and all relevant facts. Once the CRA receives it, the Minister must reconsider the assessment and vacate, confirm, vary or reassess it, then notify you in writing. The CRA gives a case number, which should go in all later correspondence.

If you withheld information during the audit or in response to a CRA request and give it only with your objection, the file may be sent back for a second review. This is a practical reason to respond to audit requests fully and on time.

You cannot object to an issue on which you waived the right of objection in writing. If you signed a waiver during the audit, get advice before assuming you can object.

Deadlines

The 90 days run from the day the notice was sent, not the day it was received. Some reassessments made under listed provisions have only the 90-day limit. If the deadline has passed, an extension application must be made within one year after it expired.

Preparing and filing the objection

• Your name, mailing address, daytime phone number, and account number.
• The notice date and the tax year.
• The facts and reasons you disagree with each audit adjustment, with copies of supporting documents.
• Your representative's details, if any, and your signed and dated notice.

You can file through My Account for Individuals or My Business Account by selecting "Register my formal dispute", or through a representative using Represent a Client. You can also mail or fax a form or signed letter to the Chief of Appeals. Form T400A was cancelled as of 2026-10-26 and replaced by Form RC592, Notice of Objection.

Payment, timing and next steps

Generally, you do not have to pay disputed income tax until the objection review is complete, though interest keeps accruing unless you pay. After a notice of objection is served, the Minister generally cannot take collection action on the disputed amount until 90 days after the day notice of the decision confirming or varying the assessment is sent, but this does not apply to some amounts, such as amounts that must be withheld and remitted, amounts under Part VIII or s.281, certain s.116 tax, related penalties and interest, or cases where CRA treats an amount as in jeopardy.

Processing times vary. For objections resolved in August 2026, the average was 145 days for low complexity and 403 days for medium complexity, and high complexity was over 690 days. If the CRA confirms the assessment, you can appeal to the Tax Court within 90 days.

• Find the notice date and calculate your deadline.
• Review the audit file, proposal letter and your earlier responses.
• Gather documents the auditor did not have.
• Get advice on whether to object and how to frame it.

Frequently asked questions