- A notice of assessment is the CRA's first result of examining your return, and a notice of reassessment changes it later.
- The CRA can generally reassess within three years of the original notice, or four for mutual fund trusts and corporations other than CCPCs.
- A reassessment starts new objection rights over the reassessed items.
After you file a return, the CRA sends a notice of assessment. Months or years later you may receive another notice, called a notice of reassessment. Many people assume the second one is just a copy of the first, but it can change what you owe.
Understanding the difference helps you see why it was issued, how long the CRA has to issue one, and what you can do if you disagree.
This article covers Canadian federal tax law, which applies in every province.
What a notice of assessment is
Under the Income Tax Act, the Minister examines a return, assesses tax, interest and penalties, and sends a notice of assessment to the person who filed it. It is the CRA's official result for that return.
An assessment is deemed valid and binding despite any error, defect or omission, subject to objection, appeal and reassessment. In plain words, you cannot ignore it just because it looks wrong. You must use the dispute process.
What a notice of reassessment is and when it happens
A reassessment is a later assessment of the same return that changes the earlier result. 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.
There are exceptions. The Minister may reassess after the normal period for misrepresentation attributable to neglect, carelessness, wilful default or fraud, or where the taxpayer filed a prescribed waiver within the normal period.
Reassessments can also help you. An individual (other than a trust) or graduated rate estate may ask for a reassessment to claim a refund or reduction up to 10 calendar years after the end of the taxation year. That is a request for adjustment, not an objection.
Side-by-side comparison
| Point | Notice of assessment | Notice of reassessment |
|---|---|---|
| What it is | First result of the CRA examining a return | A later notice that changes the earlier result |
| Timing | Sent after filing | Normally within three years of the original notice, four for some filers, with exceptions |
| Objection rights | Can be objected to | Starts new objection rights over the reassessed items |
The rights a reassessment triggers
A notice of reassessment issued within or after the normal period starts new objection rights over the reassessed items. Exactly which items count as reassessed depends on your notice, so it is worth confirming with a lawyer or accountant.
For most individuals (other than trusts), the objection deadline is the later of one year after the return's filing deadline and 90 days from the date of the notice. The 90 days run from the day the notice was sent, not the day you received it. Corporations have 90 days.
Some matters have only a 90-day limit even for individuals, including loss determinations and RRSP or TFSA over-contribution assessments.
An objection must be in writing and set out the reasons and all relevant facts. Penalties and interest are part of the assessment, so a notice of objection can dispute them.
What you cannot object to, and what to do next
Not every CRA document is an assessment. You cannot object to a statement of account or an auditor's proposal letter. CRA lists other examples, including RRSP or TFSA room statements, carryforward balances, refund interest and nil assessments. Objections filed late or before the notice was issued may be invalid.
If you decide to object, the notice of objection is addressed to the Chief of Appeals at a CRA District Office or Taxation Centre. You can file online through My Account for Individuals or My Business Account by selecting "Register my formal dispute", and you receive a case number. CRA's Form T400A was cancelled as of 2026-10-26 and replaced with Form RC592, Notice of Objection.
After it receives your objection, the Minister must reconsider the assessment and vacate, confirm, vary or reassess it, then notify you in writing. If the CRA disagrees with you, you can then appeal to the Tax Court within 90 days. Generally, you do not have to pay disputed income tax until the objection review is complete, but amounts you were required to withhold and remit must still be paid on time.
- Find the date the notice was sent and write down your likely deadline.
- Compare the reassessment with your original assessment and note what changed.
- Confirm the notice is actually an assessment, reassessment or determination.
- Collect the documents behind each changed item.
- Talk with a lawyer or accountant about whether to object, and about any penalty or interest relief.
Frequently asked questions
Is a reassessment bad news?
Not necessarily. A reassessment can increase tax, but it can also reduce it or give a refund. Individuals may ask for one to claim a refund or reduction up to 10 calendar years after the end of the taxation year.
How long can the CRA wait before reassessing me?
The normal period is three years after the original notice, or four years for mutual fund trusts and corporations other than CCPCs. It can be longer for misrepresentation attributable to neglect, carelessness, wilful default or fraud, or if a prescribed waiver was filed.
Do I get a new deadline to object?
A reassessment starts new objection rights over the reassessed items. The deadline runs from the day the notice was sent, not the day it arrived.
Can I object to a statement of account?
No. You cannot object to a statement of account or an auditor's proposal letter. You can object to an assessment, reassessment, determination or redetermination.
Sources
- Income Tax Act, s.165 (Justice Laws) — Justice Laws (federal)
- CRA Guide P148 — canada.ca
- CRA – File an objection – Income tax — canada.ca
- Income Tax Act, s.152 (Justice Laws) — Justice Laws (federal)
- Income Tax Act, s.220 (Justice Laws) — Justice Laws (federal)
- CRA – T400A page — canada.ca
- CRA – File an appeal to the Court – Income tax or GST/HST — canada.ca
Links go to official government, court and regulator pages. The law changes — confirm you are reading the current version.
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