The short version
- A notice of assessment is CRA's answer to your return: what it accepted, what it changed, and whether you get a refund or owe.
- Read the “explanation of changes” first. If it's blank, CRA accepted your return as filed.
- It also shows your RRSP deduction limit for next year, and the date that starts your objection deadline.
- Disagree? You can object until the later of 90 days after the notice date or one year after the filing due date.
- Being assessed isn't the end: CRA can generally reassess within three years of the original notice.
Notice of Assessment Explained
Every year, a few weeks after you file, CRA sends a notice of assessment. Most people check one number, the refund or the balance, and file the rest in the drawer with the warranty cards. That's fine most years. But this is the document that tells you if CRA changed your return, and it starts a clock you'll want to know about.
Can't make sense of yours? Upload it to the tax document analyzer, and it explains each section and the deadline in plain English.
What's on the Notice
| Section | What to check |
|---|---|
| Date of the notice | Write it down. Your objection deadline counts from it. |
| Account summary | Refund, balance owing, or nil. A balance is due by April 30, and interest runs daily from May 1. Refund smaller than expected? See why refunds get reduced. |
| Tax assessment summary | Total income (line 15000), net income (23600), taxable income (26000), and the tax. Compare with your copy of the return. |
| Explanation of changes | Every line CRA changed, and why. The most important part of the page. |
| RRSP deduction limit statement | How much you can deduct for RRSP contributions next year, and any unused contributions carried forward. |
| Carryforward amounts | Unused tuition, capital losses and similar amounts you can use later. |
| Access code | An 8-character code you may be asked for when filing online next year. |
Your tax-free savings account room isn't on the notice; it's in My Account.
Where It Comes From
If you signed up for online mail, the notice goes to My Account and CRA emails you that mail is waiting. Otherwise it comes by post. Some tax software shows an “express” notice right after you file online, before the official one arrives. Either way, My Account keeps a copy of every notice going back years, which beats the drawer.
How long it takes: CRA's 2026-27 goal is 2 weeks for returns filed online and 12 weeks on paper. More on timing in where's my tax refund.
Notice says CRA changed something?
Upload it. The Tax Document Analyzer reads the explanation of changes, tells you which line moved and why, and works out your objection deadline.
If CRA Changed Something
The explanation of changes is usually one of these:
- Math or transfer errors. CRA corrects arithmetic or a carry-forward amount. Usually right.
- A limit applied. A claim over its maximum, or the RRSP deduction over your limit.
- A slip that doesn't match. More common in a later reassessment, after CRA's matching program runs. See missing T4.
- A claim CRA didn't accept, sometimes because it asked for receipts and didn't get them.
Then decide. If CRA is right, pay the balance; interest is charged daily. If CRA is missing a receipt, send it through Submit documents in My Account. If CRA is wrong on the facts or the rules, you can ask for a change or file a formal objection. The objection deadline is the later of 90 days after the date on the notice or one year after your filing due date. The objection deadline calculator works it out.
Disagree with CRA? File the objection properly
The Objection Pack reads your notice, works out your deadline, drafts your statement of facts and fills in form T400A for you to sign.
Assessment, Reassessment, Confirmation
- Notice of assessment: the first answer to your return.
- Notice of reassessment: CRA went back and changed an assessed return, because of a review, a matching slip, or your own change request. See notice of reassessment: what to do.
- Notice of confirmation: CRA's answer to an objection, when it doesn't change anything. The next step from there is the Tax Court of Canada.
CRA can generally reassess an individual's return within three years of the date on the original notice of assessment. Longer in some cases, such as misrepresentation, loss carrybacks, or an unreported sale of a home. That's one reason to keep records for six years. Our CRA guide covers the other letters.
Spotted Your Own Mistake?
Wait for the notice, then change the return yourself, before CRA finds it. Online changes are usually processed in about two weeks. Read how to change your tax return. If it's a bigger problem, like income you never reported, a voluntary disclosure may reduce penalties; see CRA tax problems.
Four Notice of Assessment Rules of Thumb
- Read the explanation of changes, even when you got a refund.
- Write the notice date on your calendar with the objection deadline beside it.
- Use the RRSP limit from the notice, not last year's guess.
- Keep every notice until at least six years after the tax year.
Want fewer surprises on the notice? Return Check reviews the return before you file, against the changes CRA makes most.
Want it read for you? Upload it to the notice of assessment analyzer.
Notice of Assessment Questions
What is a notice of assessment?
A notice of assessment is the statement CRA sends after processing your tax return. It shows your income and tax as assessed, any changes CRA made and why, your refund or balance owing, and your RRSP deduction limit for the next year.
How long does it take to get a notice of assessment?
CRA's 2026-27 service standard is 2 weeks for returns filed online and 12 weeks for paper returns.
Where do I find my notice of assessment?
In CRA My Account, under mail or tax returns, where past notices are also stored. If you are not signed up for online mail, a paper copy is mailed to you.
What do I do if I disagree with my notice of assessment?
Send missing documents if that is all CRA needs, request a change, or file a formal objection. For income tax, the objection deadline is the later of 90 days after the notice date or one year after the filing due date for that return.
Can CRA change my return after the notice of assessment?
Yes. CRA can generally reassess within three years of the date of the original notice of assessment, and longer in some situations such as misrepresentation.
Sources: CRA, After sending us your tax return; Service Standards 2026-27; P148 Resolving your dispute; Changing a tax return. Checked October 2026. The layout of the notice changes from time to time; section names may differ slightly.
Last reviewed October 5, 2026 against CRA and Government of Canada sources. How we check our facts.