Receiving a Notice of Reassessment from the Canada Revenue Agency can stop you in your tracks. The envelope looks official, the language is dense, and the numbers can be confusing — especially if you weren't expecting it. But a Notice of Reassessment is actually one of the more common letters the CRA sends, and once you understand what it means and what to do, you can respond with confidence.
What Is a Notice of Reassessment?
A Notice of Reassessment (sometimes abbreviated NOA or T7WC) is a letter the CRA sends after it has reviewed your original tax return and made one or more changes to it. Think of it as the CRA revising their initial assessment of your taxes.
The outcome of that revision falls into one of three categories:
- You owe more tax — The CRA found income you didn't report, disallowed a deduction or credit you claimed, or corrected a calculation error in their favour.
- You're owed a larger refund — The CRA found an error in your favour, such as a credit that was miscalculated.
- No change to your balance — An administrative adjustment was made to your file, but your refund or balance owing didn't change.
The notice will always show your revised tax balance, a breakdown of what changed, and the reason codes explaining why the change was made. It will also display any new amount owing or refund, along with the deadline by which you need to act.
Why Would CRA Send You One?
Many Canadians assume that a reassessment means they did something wrong. That's not always the case. There are several routine reasons the CRA reassesses a return:
1. The matching program CRA's automated systems compare your filed return against all the information slips submitted by third parties — your employer's T4, your bank's T5, your investment platform's T3, and so on. If anything doesn't match, the system flags it for review. This is the single most common trigger for a reassessment.
2. A random review Every year, CRA selects a percentage of returns for random manual review — even if everything looks correct. If you're selected, a reassessment may follow as a result of that review.
3. A request you submitted If you filed a T1 Adjustment Request (T1-ADJ) to correct your own return, the Notice of Reassessment is CRA's formal confirmation of that change.
4. A third-party tip In some cases, CRA receives information from a third party about an individual's tax affairs. They are required to investigate and, if warranted, will reassess accordingly.
5. An audit outcome If you were subject to a CRA audit, the Notice of Reassessment is the formal result of that audit. It will reflect all changes made as a result of the audit findings.
6. A benefit review Reassessments can also follow reviews of specific benefits — like the Canada Child Benefit or the GST/HST Credit — where CRA determines that the amount you received was incorrect.
How to Read the Notice
The notice is divided into sections. The most important are:
- Summary of changes — Lists each line number on your return that was modified and the old versus new value
- Reason codes — A short code (e.g., "A12" or "B7") that identifies the legal basis for the change; you can look these up on the CRA website
- Balance due or refund — Your new financial position after the change
- Interest charges — If you owe more, CRA will have already started calculating daily interest from the original filing deadline
- Objection deadline — The date by which you must file a formal objection if you disagree
Read every section carefully before you do anything else.
What to Do When You Receive One
Step 1: Don't ignore it
A Notice of Reassessment is a legally significant document. Ignoring it doesn't make it go away — it simply removes your ability to challenge it. Put it somewhere safe and address it promptly.
Step 2: Verify the change against your own records
Pull out your original tax return and all supporting documents. Check whether the change CRA made is actually correct. Common errors you may find:
- An income slip you genuinely forgot to include
- A deduction CRA disallowed that you believe you're entitled to, and for which you have supporting receipts
- A calculation CRA made that doesn't match the rules as you understand them
Step 3: Determine whether you agree or disagree
If CRA is right, your path is simple: pay any balance owing promptly to stop interest from accumulating further. Interest on overdue tax balances compounds daily at the CRA prescribed rate, which is currently set quarterly.
If you disagree with the reassessment, you have the right to object formally — but you must act within the deadline printed on the notice.
Step 4: File a Notice of Objection if you disagree
You have 90 days from the date on the reassessment to file a Notice of Objection. This is done through:
- CRA My Account — Under "Register my formal dispute"
- Form T400A — Filed by mail to your tax services office
In your objection, you need to state clearly which part of the reassessment you're disputing, the facts supporting your position, and the reasoning for why you believe the CRA's change is incorrect. Include copies (not originals) of any supporting documents.
Step 5: If you need more time to pay
If you agree with the reassessment but can't pay the full balance immediately, contact CRA's payment arrangements line (1-888-863-8657) before the due date. CRA can set up a payment plan. This doesn't eliminate the interest, but it does prevent the account from going to collections prematurely.
What Happens If You Don't Respond?
Missing the objection deadline without applying for an extension will forfeit your right to dispute the reassessment through the standard process. At that point, your only avenue is to apply to the Tax Court of Canada — a significantly more complex and costly process.
On the financial side, any unpaid balance will:
- Continue accumulating compound interest
- Be referred to CRA's collections division
- Potentially result in a wage garnishment, bank account hold, or a lien registered against property
None of these outcomes are inevitable if you act promptly. The CRA generally prefers to resolve balances through payment or objection rather than through enforcement.
How Long Does CRA Have to Reassess?
Generally, CRA has three years from the date of the original Notice of Assessment to reassess your return — this is called the normal reassessment period. After that, your return is typically considered closed.
However, there are important exceptions. CRA can reassess beyond the normal period if:
- There was misrepresentation attributable to neglect, carelessness, or wilful default
- There was fraud
- You waived the limitation period (for example, if you asked CRA to hold off while you gathered documents)
In cases involving foreign income or complex transactions, extended reassessment periods may also apply.
Need Help Decoding Your Specific Letter?
Every Notice of Reassessment is different. The reason codes, the amounts, the credits at issue, and the deadlines all vary from case to case. CRA Navigator analyses your specific letter and gives you a personalised plain-English explanation of exactly what CRA changed, why, what you owe or are owed, and a step-by-step action plan for your situation.