When the CRA asks a question: what to do first

Current to September 11, 2026.

The letter is rarely as serious as it feels. Do not panic. Do answer it, on time and to the point.

Not all CRA contact is the same, and the first useful step is working out which kind you have. Most of what arrives is a review letter, sent under the Processing Review Program: the return has already been assessed, and the CRA is now asking you to support something claimed on it.

A desk audit examines a defined area in more depth. A full audit is broader and involves an assigned auditor, and in an audit the CRA will usually set out the position it intends to take and give you a window to answer before assessing. A notice of reassessment is a decision, and a different clock starts.

What to do

Answer within the time given, or ask for more. Extensions are commonly granted when requested before the deadline and rarely after it. Silence is treated as an inability to support the position, and the claim is disallowed on reassessment.

Answer the question that was asked. Supporting documents for the item under review, and no more. Volunteering unrelated material invites the scope to widen, and it frequently does.

Keep it in writing. Phone calls are efficient and leave no record. Confirm anything substantive by letter or through the portal, so there is a version of events that does not depend on memory.

Deal with it before the reassessment, not after. It is materially easier to change a position while the review is still open than to object once it has been assessed.

If the review deadline has already passed

Missing it is not ideal. The claim is disallowed, a reassessment follows, and that can bring a demand for payment along with interest. It is usually recoverable. A return can generally be adjusted after a reassessment, provided the supporting documents are submitted to the CRA at that point — the same documents the review letter asked for. The position is worse than it would have been, not lost.

This is a different deadline from the one on a notice of objection, and a far more forgiving one. Do not read what follows as applying to a missed review letter.

If you disagree with an assessment

Disagreeing with the assessment itself is a separate route with a stricter clock. A notice of objection is the formal step. Its deadline runs from the date of the notice of assessment or reassessment, though for individuals and testamentary trusts an alternative longer period can apply, measured from the filing due date for the year. Which one governs is worth confirming rather than assuming, because the shorter of the two is the one people apply to themselves by mistake.

Missing the objection deadline is not always fatal. An extension can be applied for, and that application has its own outer limit. But an objection is not adjustable the way a return is, and relying on the extension is a poor plan. Appeals to the Tax Court follow the objection stage, not instead of it. Objecting also affects what the CRA can do to collect in the meantime, and the rules on that are not the same for every kind of assessment.

Most matters do not get that far. They are resolved at the review stage by producing the right documents with a clear explanation of what they show. Where the review concerns an area the CRA has been actively gathering third-party data on, such as cryptocurrency, the position is worth checking before responding rather than after. See tax.