Got a CRA reassessment? What to do first

1. Don't panic — and don't ignore it

A reassessment is the CRA's position, not the final word. You have a formal right to dispute it through a notice of objection. But ignoring the notice doesn't pause anything: interest keeps accruing on any amount owing while you decide.

2. Find the date printed on the notice

This is the single most important detail. A notice of assessment is legally presumed sent on the date printed on it (ITA s.244(14)) — not the day you opened it, not the day it arrived. That printed date is Day 0 for your objection deadline, and counting starts the day after.

If your notice arrived electronically through My Account, different deemed-sent rules apply (s.244(14.1)–(14.2)) — confirm which date counts.

3. Check your deadline immediately

For most taxpayers the deadline is 90 days after the notice was sent. Individuals get the later of that and one year after the filing-due date (ITA s.165(1)); GST/HST is a flat 90 days (ETA s.301(1.1)). Run the numbers now — deadlines are strict, and the late-extension route is discretionary.

4. Figure out which track you're on

Ask yourself: is my problem the assessment itself (income added, deductions denied, credits reduced) — or only penalties and interest?

• Assessment itself → a notice of objection is the formal track.
• Penalties and interest only → a taxpayer relief request (Form RC4288) is the separate track. It can only ask the CRA to cancel or waive penalties and interest; it cannot change the tax owing, and there's no right of objection or appeal on relief decisions.

Objection vs. taxpayer relief — the full comparison →

5. Start gathering your documents now

A valid objection must clearly explain what you're objecting to and why, set out the reasons and all relevant facts, and include supporting documentation. Don't wait until week twelve to start looking for receipts. Depending on your issue: slips and contracts (income), receipts and invoices (deductions), eligibility documents (credits), sales invoices and ITC records (GST/HST).

6. Know the honest trade-offs

• Paying now saves interest even if you later win — interest accrues during the whole dispute.
• Filing generally suspends collections on the disputed amount until 90 days after the Minister's decision is sent (ITA s.225.1(2)), with exceptions.
• It takes months. Actual June 2026 CRA averages: 127 days (low-complexity), 389 days (medium), 690+ days (high-complexity).
• Complex cases need a lawyer. Very large amounts, GAAR, transfer pricing, cross-border issues, or criminal tax matters are not DIY territory.