Updated Checked by the Tax-Services.ca editorial team How we check
You can appeal a CRA audit decision by filing a notice of objection. If you’re an individual, the deadline is the later of one year after the filing deadline for that return or three months from the day your notice of assessment or reassessment is dated, counted as 90 days. Miss it and you’ll have to ask for an extension.
What does it mean to appeal a CRA audit decision?
The audit itself isn’t the decision you appeal. The audit ends with the CRA changing your return, and that change arrives as a notice of assessment or reassessment. The notice carries a date, and that date starts your clock. Not the last phone call, not the last letter from the auditor.
An objection asks another branch of the CRA, the Appeals Branch, to look at the file again. The CRA describes that review as impartial, so the auditor who made the change isn’t the person deciding. That’s the point of the process.
What are the deadlines?
| Step | Time limit |
|---|---|
| Objection by an individual (not a trust) | Whichever is later: a year past the return’s filing deadline, or 90 days after the notice is dated |
| Objection in other cases | 90 days counted from the notice’s date |
| Ask for extra time after missing the deadline | Within 1 year after the objection deadline |
| Go to the Tax Court of Canada | 90 days after its decision goes out, or 90 days after you objected if it never answers |
Count from the date printed on the notice, not the day it reached you. The CRA’s page on filing an income tax objection has the rules for individuals, and it says RRSP and TFSA objections and corporations get the 90 days only.
How do you file the objection?
There are three routes. Sign in to My Account (or My Business Account) and choose the option to register a formal dispute. Or post or fax form T400A to the Appeals Intake Centre. Or send a signed letter.
Whichever you pick, include your contact details, the tax year, the notice’s date, your account number, and your reasons with the facts behind them. Attach the papers that back you up. Say what you dispute and why, in plain sentences. A page and a half beats ten pages of grievance. If your deadline is close, file first and add papers afterward.
Don’t argue that the auditor was rude. Argue that the $5,000 deduction was real, and show the receipts.
What does a good objection actually say?
Keep it to four moves. Name the notice and the line you dispute. State what you think the correct figure is. Give the facts that support it, in date order. And list the documents attached, so the reviewer can tick them off.
Say your reassessment disallowed a $5,000 home office claim. A good objection names the year, says the claim was for the part of the home used only for work, and attaches the floor plan, the utility bills and the lease. A bad one says “this is unfair” and stops there.
What does a disputed audit change actually cost?
Take a person earning $80,000 in Ontario. With the income tax calculator, income tax comes to $14,127.85. Enter a $5,000 deduction and it drops to $12,645.35. So if an auditor disallows that deduction, the extra tax is $1,482.50, before any interest or penalty, which the calculator doesn’t model.
That gap tells you whether the fight is worth it. To see how much each added dollar of income costs you, try the marginal tax rate calculator. And if the reassessment turns out to be wrong in your favour, the tax refund calculator gives a rough idea of what comes back. For business owners, the self-employed tax calculator shows the same effect with CPP added.
Do you have to pay while you wait?
The CRA usually waits before it chases the disputed sum, for 90 days after its decision. Interest keeps running on what you owe, though. If you lose, you’ll pay that interest too. Large corporations are treated differently and must pay 50% of the disputed amount when they object.
The CRA has also said it’s getting more objections than usual, so some take longer to process. Plan for months, not weeks, and keep every reply the CRA sends you in one folder, because the reviewer may ask for the same paper twice and you’ll want it in your hand the first time.
Mistakes and limits
The most common slip is waiting for the auditor to change their mind and letting the objection window close. Talking to the auditor doesn’t stop the clock. Another is sending a letter with no reasons. The CRA asks for facts and reasons, so an objection that says only “I disagree” gives the reviewer nothing to work with.
Watch the deadline for other taxes too. This page covers income tax objections. GST/HST and payroll disputes have their own pages on canada.ca, and we haven’t confirmed their time limits here, so check before you assume they match.
Should you hire someone? If the amount is large or the issue is technical, an accountant or lawyer who handles disputes is worth a call. For a few hundred dollars of disallowed expenses, most people handle it themselves. We don’t offer or recommend any such service.
What this page is based on
The objection deadlines and steps here were read from the CRA‘s guide P148 and its objection pages in September 2026. Tax figures come from the 2026 federal and Ontario tax data used by our calculators. We aren’t a government service and we don’t speak for one.
Frequently asked questions
How long do I have to appeal a CRA audit decision?
An individual has until the later of a year after the return's filing deadline, or 90 days counted from the date on the notice. Other cases get 90 days.
Can I appeal after the deadline?
You can ask for an extension. The request must be made within one year after the objection deadline, and you need a reason such as circumstances beyond your control.
Do I pay the tax while the objection is open?
Normally the CRA waits before it collects the disputed amount. Interest still builds on what you owe.
What if the CRA confirms its decision?
Take it to the Tax Court of Canada, within 90 days after the CRA's decision goes out.
What should an objection include?
Contact details, the tax year and notice date, your account number, and your reasons with the facts and supporting papers.
- Dealing with the CRA: letters, audits and payments
Dealing with the CRA: what to do when a letter arrives, how a review differs from an audit, how My Account helps, and what to do if you can't pay