Notice of Objection Deadline in Canada: The 90-Day Rule Explained

When the CRA assesses or reassesses you and you disagree, the formal way to dispute it is a notice of objection. That notice has a deadline, and the deadline is easy to misread. Many people assume it starts when the letter arrives, or that it is always 90 days.

This article explains when the clock starts, how the deadline differs between individuals and corporations, and which assessments have shorter limits. It is general information about federal income tax, not advice on your file.

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

What a notice of objection is

After you file a return, the Minister examines it, assesses tax, interest and penalties, and sends a notice of assessment to the person who filed it. If you disagree, the Income Tax Act requires a written notice of objection that sets out the reasons for the objection and all relevant facts.

CRA says objections can be filed against a notice of assessment, reassessment, determination or redetermination. The same rights apply to determinations such as the Canada child benefit, the GST/HST credit, the disability tax credit and loss determinations.

When the 90 days start

The 90 days run from the day the notice of assessment was sent, which is the notice date. They do not run from the day you received it. Look at the date printed on the notice itself, and keep the envelope or the online notice record.

This matters if your mail was delayed or you opened the notice late. A late reading does not move the deadline. If you are close to the limit, treat the notice date as day one of your countdown and file well before the end.

Who gets 90 days and who gets longer

The deadline depends on who you are. Corporations and other taxpayers who are not individuals have 90 days after the notice of assessment was sent. An individual (other than a trust) or a graduated rate estate has until the later of one year after the taxpayer's filing-due date for the year and 90 days after the notice was sent. CRA guidance describes it the same way.

In practice the longer individual deadline often applies to a first assessment shortly after filing. For a reassessment issued years later, the 90 days after the new notice may be the later date. Which date is later depends on your facts, so confirm it before relying on it.

Exceptions and special cases

• Under section 165(1.1), the 90-day limit also applies to reassessments made under certain listed provisions.
• A large corporation's notice must reasonably describe each issue, state the relief sought for each issue, and give the facts and reasons. If information is missing, the Minister may request it and the corporation has 60 days to provide it.
• You cannot object to an issue on which you waived the right of objection in writing.
• You cannot object to a statement of account or an auditor's proposal letter. A taxpayer in a loss position cannot object until a notice of loss determination is issued.
• Examples that cannot be objected to include RRSP or TFSA room statements, carryforward balances, Home Buyers' Plan balances, refund interest and nil assessments. Objections filed late or before the notice was issued may be invalid.

Reassessments restart the clock for reassessed items

The normal reassessment period is three years after the original notice of assessment, or four years for mutual fund trusts and corporations other than CCPCs. A notice of reassessment issued within or after that period starts new objection rights over the reassessed items. The Minister can reassess after the normal period in some cases, such as misrepresentation attributable to neglect, carelessness, wilful default or fraud.

New rights apply to the reassessed items, not necessarily to everything on the return. If you want to dispute an item that was not changed, the original timing may still govern.

What to do next

• Find the notice date on the assessment or reassessment and write down your deadline.
• Work out whether you are in the individual, corporate or shorter-limit category.
• Gather the facts, reasons and supporting documents for each item you dispute.
• File through My Account, My Business Account or Represent a Client by selecting "Register my formal dispute", which gets a case number. CRA says portal objections are assigned to an appeals officer sooner than paper.
• If filing on paper, note that CRA's Form T400A was cancelled as of 2026-10-26 and replaced by Form RC592, Notice of Objection, a fillable PDF that must be opened in Acrobat Reader 10 or later. A signed letter to the Chief of Appeals is also an option.
• Keep the case number for all later correspondence.

If the deadline is close or already behind you, speak with a lawyer or accountant promptly about your options.

Frequently asked questions