A Notice of Reassessment means the CRA has reviewed a return that was already assessed and changed it – often affecting your tax owing, refund, penalties, and interest. What matters now is doing the right things in the right order – especially before the clock runs out.
Step 1: Do this today (the “don’t-miss-a-deadline” checklist)
- Find the notice date (the date on the notice).
This date generally drives your objection deadline. Determine your objection deadline. - Identify exactly what changed.
Compare the reassessed amounts to your original filing (income, deductions, credits, penalties, interest). - Pull every CRA letter that led up to this.
Reassessments often follow a review/audit where the CRA requested documents. - Collect your proof.
Receipts, invoices, contracts, bank records, bookkeeping reports, slips, correspondence—anything that supports your original position. - Calendar the objection deadline immediately.
Make sure that you document your objection deadline and do not miss it.
Step 2: Choose the right path (not every reassessment needs a fight)
A reassessment usually falls into one of these situations:
A) You agree with the change
Pay what’s owed (or set up a payment arrangement). Interest can keep accumulating on balances owing.
B) You disagree (facts misread or law misapplied)
That’s when a Notice of Objection is usually the next step. Objections are for situations where you believe they misinterpreted your facts or applied the law incorrectly.
Step 3: Know the deadline that matters most
Individuals (and graduated rate estates)
Your objection deadline is generally whichever is later:
- 1 year after the tax filing deadline for the return, or
- 90 days from the date of your notice of reassessment.
Corporations
Your objection deadline is generally:
- 90 days from the date of your notice of reassessment.
Missed the deadline?
You may apply for an extension, and the CRA states you can apply up to one year after the objection deadline (and you can apply at the same time as you file your objection).
Step 4: File a Notice of Objection
The CRA’s guidance is straightforward: when you object, you must clearly explain what you’re objecting to and why, and include relevant facts and supporting documentation.
What to include in a strong objection
- The tax year and the Notice of Reassessment you’re objecting to
- The specific items you disagree with (line items/issues)
- A clear explanation of why (facts + law, where relevant)
- The documents that prove your position
- A summary your reviewer can follow quickly
How to file
You can file:
- Online in CRA portals (My Account / My Business Account) using “Register my formal dispute”, and then upload documents through “Submit documents online.”
- Through your authorized representative via Represent a Client
- By mail/fax using Form T400A (Objection – Income Tax Act) or a signed letter with the facts, reasons and the same information that would go into a T400A form.
Step 5: Does interest continue to accrue while you object?
Interest charges continue to accrue while the amount is in dispute. You can pay the amount in dispute to avoid additional interest.
Step 6: What happens after you object?
Once you file, the CRA reviews what you submitted and will either:
- agree (in whole or part) and issue an adjustment/reassessment, or
- disagree and send a notice saying the reassessment/determination was correct
Step 7: If the CRA says “no,” the next step is Tax Court
If you disagree with the CRA’s decision on your objection, you can appeal to the Tax Court of Canada. Generally, you have 90 days from the CRA’s reassessment /determination following your objection to file your appeal.
How far back can the CRA go?
Under the Income Tax Act, the “normal reassessment period” is generally:
- 4 years for a mutual fund trust or a corporation that is not a CCPC, and
- 3 years in most other cases, counted from the day the CRA sent the original assessment (or the original “no tax payable” notification).
The CRA can reassess after that normal period in specific situations – such as where there was a misrepresentation attributable to neglect, carelessness, wilful default, or fraud, or where a waiver was filed.
One more option people miss: relief from penalties and interest
If your main issue is penalties and/or interest (not the underlying tax), you may be able to request taxpayer relief (discretionary, fact-driven). There’s also a 10‑year limitation period for interest relief requests (and related limits for penalties/interest outside the eligible window).
Bottom line
A CRA Notice of Reassessment isn’t the end of the road – but it is a deadline-driven process. If you believe the reassessment is incorrect, the goal is to:
- lock in your deadlines,
- build an evidence-based position, and
- file a clean, timely objection that’s easy for CRA to understand.
If you want help assessing the notice, preparing your objection, or planning next steps (including Tax Court strategy), contact Taxpayer Law today.
