What is a CRA notice of assessment, and what should I check on it?

A notice of assessment (NOA) is the CRA's summary of how it assessed your tax return: the refund or balance owing, the key lines it accepted or changed, and an explanation of any changes. If you file online it usually appears in your CRA account as soon as the return is processed. If you disagree with it, the normal deadline to object is 90 days from the date on the notice (for individuals, one year after the filing deadline if that is later).

Updated October 30, 2026. Figures from the CRA pages linked below.

When it arrives

Personal returns (T1): the CRA's service standard is to process 95% of on-time electronic returns within 4 weeks and paper returns within 8 weeks. Late returns and returns under review take longer.
Corporate returns (T2): the CRA aims to send the NOA within 8 weeks of a digitally filed return. It comes through My Business Account, online by default, or by mail.
Online mail is the default: you get an email that a notice is ready; the notice itself is in your CRA account, not in the email.

What to check on it

Account summary: the refund or balance owing. A balance owing keeps earning interest, compounded daily, at the CRA's prescribed rate (7% on overdue taxes for October to December 2026).
Changes: any line the CRA changed, with its explanation. Compare it to the return you filed.
RRSP deduction limit: your room for next year, plus any Home Buyers' Plan or Lifelong Learning Plan repayment due.
Carryforwards: amounts such as unused losses or tuition that matter for next year's return.

If something is wrong

A simple error you made: wait for the NOA, then use Change my return in your CRA account, ReFILE through your preparer, or form T1-ADJ by mail. Adjustment requests generally go back 10 calendar years for individuals.
You disagree with the CRA's decision: file a notice of objection. Individuals have the later of 90 days from the notice date or one year after the filing deadline; corporations have 90 days. Corporations can object online in My Business Account or on form T400A. An extension can be requested up to one year after the deadline.
GST/HST: correct a filed GST/HST return with Adjust a return in your CRA account; do not file a second return.

Reassessment: how long the CRA can come back

Individuals and Canadian-controlled private corporations: generally 3 years from the date of the original notice of assessment.
Other corporations: 4 years.
Longer in some cases: 3 more years for certain items, and no limit for misrepresentation or where a waiver was filed. A change after the NOA arrives as a notice of reassessment.

Worked examples (estimates for illustration)

Kelowna electrician, sole proprietor: filed online May 1; NOA dated May 20 shows a $1,850 balance owing with no changes. Paying it now stops further daily interest.
Vernon contractor, missed T4A slip: NOA dated June 10 adds $3,200 of income from a slip left off the return. That is the CRA matching slips, not a dispute; if the slip is correct, pay or arrange payment. If it is wrong, the payer issues an amended slip and you ask for an adjustment.
Penticton corporation: T2 NOA dated March 15 disallows a $12,000 expense. The 90-day objection window ends June 13.

FAQ

Do I need to keep my notice of assessment?
Yes. Lenders often ask for it to confirm income, and it shows your RRSP room. You can download past notices from your CRA account.

Can I change my return before the NOA arrives?
The CRA asks you to wait for the NOA before requesting a change.

Does a notice of reassessment mean the CRA examined my whole return?
Not always. Many reassessments come from slip matching or a request for documents on one item.

Every situation is different, so talk to your accountant about your specifics.

Want a second set of eyes? Email info@murtaghco.ca or book a 30-minute call. Devon Murtagh, CFA, FRM.

Sources: CRA: Notice of assessment and reassessment; CRA: After sending us your tax return; CRA: Processing times; CRA: After you file your T2 return; CRA: Resolving disputes, corporations; CRA: Prescribed interest rates, Q4 2026; Income Tax Act s.152.