Every year, after you file your return, the Canada Revenue Agency sends back a Notice of Assessment — and for most people it lands with a small jolt of anxiety before it is even opened. Then, weeks or months later, a second letter can arrive asking you to prove a deduction or credit you claimed. Understanding your Notice of Assessment and a CRA review is far less intimidating once you know what each document is actually saying and what the agency wants from you. This guide walks through both, calmly and in plain language.
What a Notice of Assessment actually is
A Notice of Assessment (NOA) is the CRA's official summary of your return after it has been processed. It confirms whether the agency agrees with the numbers you filed, states your refund or balance owing, and records a few figures you will need later. It is not a bill in the ominous sense — for most filers it simply says "we received this, here is where you stand."
Read past the headline number and check these lines:
- Refund or balance owing — and whether it matches what your software or preparer calculated.
- Your RRSP deduction limit for the coming year, which you will need before making a contribution.
- Any unused tuition, capital losses, or Home Buyers' Plan balances carried forward.
- Explanation section — if the CRA changed anything, it says so here in a short, coded note.
If your NOA shows a different result than you expected, do not panic. The most common cause is a simple mismatch — a T-slip the CRA had on file that you did not enter, or an arithmetic correction. The explanation lines usually tell you exactly what moved.
Assessment versus review versus audit
These three words get used interchangeably, but they are very different in scale. An assessment is routine processing. A review is the CRA asking you to back up a specific claim — a deduction, a credit, or a slip — with documents. An audit is a far deeper, broader examination of your books and records, and it is comparatively rare for individuals and small businesses.
The vast majority of the letters people receive are reviews, not audits. A review is narrow and document-driven: send the receipt, the claim is verified, the file closes. Treating a review like a catastrophe usually causes more stress than the review itself warrants.
Why your return might get reviewed
Being selected does not mean the CRA thinks you did something wrong. Returns are pulled through several ordinary programs:
Pre-assessment review
This happens before your NOA is finalized, often in the spring filing season. The CRA holds the return to verify a claim first, which can delay your refund. You will be asked to send support before the assessment is issued.
Processing review program
This is the classic after-the-fact letter, typically arriving in the months following assessment. The CRA has already assessed you and is now spot-checking a deduction or credit — medical expenses, donations, child-care costs, or employment expenses are common targets.
Matching program
Later in the year, the CRA compares the slips on your return against the copies filed by employers, banks, and other issuers. If a T4, T5, or T3 does not line up, you will hear about it. This is one reason to enter every slip, even small ones.
Selection is often random or driven by a claim that is simply larger than average for your income. It is not an accusation.
A review letter is a request for paperwork, not a verdict. The calm response — the right receipts, sent on time — is almost always the whole story.
How to respond to a CRA review letter
Read the letter carefully first. It will name the exact line or claim under review, list what documents to provide, give a reference number, and state a deadline — commonly around 30 days from the date on the letter. Meeting that deadline matters, because if you do not reply, the CRA can simply disallow the claim and reassess you.
- Gather the specific support requested — receipts, official donation slips, a signed T2200 for employment expenses, or statements. Send exactly what is asked for, clearly labelled.
- Include the reference number on every page so your documents are matched to your file.
- Respond through your CRA My Account where possible; the "Submit documents" service is faster and traceable than mail.
- Keep copies of everything you send, along with a note of the date.
- Ask for more time if you need it — a brief call before the deadline is far better than silence.
If a claim was genuinely made in error, it is fine to say so and let the adjustment stand. Honesty here is cheaper than a fight.
Understanding a Notice of Reassessment
If the review changes your return, the CRA issues a Notice of Reassessment (NORA) — an updated NOA showing the new figures and any balance now owing. Interest can apply to amounts owing, so if you agree with the change, paying promptly limits the cost.
Generally, the CRA can reassess an individual or a Canadian-controlled private corporation within the normal reassessment period of three years from the date of the original Notice of Assessment (four years for many other corporations). After that window, the return is usually closed — though the CRA can reach back further in cases of misrepresentation or neglect, or if you have signed a waiver. This is exactly why keeping your records for at least six years is not just good habit but a genuine safeguard.
If you disagree: your right to object
You do not have to accept a reassessment you believe is wrong. You can file a formal Notice of Objection. For individuals, the deadline is the later of one year after the filing due date for that return, or 90 days after the date on the Notice of (Re)assessment. Corporations generally have 90 days from the notice date.
Before filing a formal objection, it is often worth a phone call or a request for an adjustment — many disputes are just a missing document and resolve without any formal process. If the matter is substantive, an objection preserves your rights and sends the file to an independent appeals officer. Missing the deadline is the costly mistake, so calendar it the moment a reassessment arrives.
Key takeaways
- Your Notice of Assessment confirms your result and records your RRSP room and carry-forwards — read past the refund figure.
- A review is a request for documents on one claim; an audit is far broader and far rarer.
- Reviews come through pre-assessment, processing review, and slip-matching programs — usually routine, not an accusation.
- Respond by the deadline (often about 30 days) with the exact support requested and the reference number.
- The CRA can generally reassess individuals within three years of the original NOA — keep records for six years.
- If you disagree with a reassessment, you can object; watch the 90-day / one-year deadline closely.
A letter from the CRA rarely needs to ruin your week. Most reviews are resolved with a tidy envelope of receipts and a bit of patience — and knowing which deadline applies is half the battle. If you have received a review or reassessment and are not sure what it is asking for, we can read it with you, assemble the right response, and deal with the CRA on your behalf. Book a consultation or learn more about our personal tax support, and let us take the worry off your desk.
This article is general information, not tax, legal, or financial advice. Rules and figures are current as of 2026 and can change. Please confirm your own situation with Lewis Partners.