First, confirm what you are holding: a review is not an audit
A review letter asks you to support specific lines on a specific return — receipts for one deduction, backup for one credit, an explanation of one mismatch. It names a program, a tax year, a reference number and a deadline, and it can usually be resolved with one well-organized package of documents. An audit is a different animal: a broader examination of your books and records, usually opened by a letter or call that names an auditor and proposes next steps. The two get confused because both arrive as official mail and both make owners' stomachs drop, but the correct response differs, so identify which one you have before doing anything else.
The tells are on the first page. Review letters cite a review or verification program, ask for documents supporting identified items, and set a response date. Audit letters name the auditor, describe the scope of examination, and start a conversation rather than a document request. If yours is an audit, the playbook changes — start with what to do after receiving a CRA audit notice. If it is a review, keep reading: handled properly, most of these are closed within weeks and never heard from again.
Timing context helps too. Reviews cluster in predictable seasons — pre-assessment and processing reviews follow the filing waves, and matching letters arrive once third-party slips have been processed against returns — so a letter landing months after you filed does not mean something new has gone wrong. It usually means your return reached the front of a queue.
One rule sits above everything else on this page: never ignore the letter. CRA does not need your response to act. If the deadline passes in silence, the reviewed claim is typically disallowed and the return reassessed, with interest running — turning a request you could have answered with a folder of receipts into a balance owing and a dispute.
What CRA review letters usually ask for
Reviews arrive through a handful of standing programs, and knowing which one sent yours tells you what it wants and how urgent it is:
| Program | When it arrives | What it wants |
|---|---|---|
| Pre-assessment review | After you file, before the notice of assessment | Support for specific claims before CRA assesses; any refund is held until you answer |
| Processing review | After the notice of assessment | Receipts and documents behind selected lines on an already-assessed return |
| Matching program | Later in the year | An explanation for differences between your return and the slips employers, banks and others filed about you |
| GST/HST return review | Usually when a return claims a refund or rebate | Invoices supporting input tax credits; the refund is held until the review closes |
| Corporate desk review | Any time after a T2 is filed | Ledgers, invoices or agreements behind specific schedules or expense categories |
Being selected is not an accusation. Some reviews are random, some are triggered by a claim that sits outside the usual pattern for your size and sector, and some — the matching program especially — are purely mechanical, generated when a slip in CRA's hands does not appear on your return. The letter's tone is procedural because the process is procedural. What converts a routine review into a problem is almost always the response: late, incomplete, or padded with material nobody asked for.
Read the letter twice before responding, because two details change everything: exactly which line items are named, and exactly which tax years. Owners regularly send the right documents for the wrong year, restart the clock, and turn a three-week review into a three-month one. The reference number matters just as much — a response that arrives without it can sit unmatched to the file while the deadline runs.
How to respond: exactly what was asked, by the deadline, in one package
Answer the question you were asked — no less, and genuinely no more. Match your package to the letter item by item: if it asks for receipts behind one expense line, send those receipts, organized and totalled to tie to the number on the return, with a short covering note quoting the reference number. Volunteering extra years, extra categories or loose explanations does not build goodwill; it widens the file. Reviews have a defined scope, and disciplined responses keep them inside it.
A response package that closes reviews on the first pass looks the same every time:
- A one-page cover letter quoting the reference number, the tax year and the items under review, listing what is enclosed.
- Documents in the letter's order, labelled to match, with subtotals that tie exactly to the figures on the return.
- A short reconciliation wherever the documents do not obviously add to the claimed number — the reviewer should never have to build your math for you.
- Nothing else. No extra years, no adjacent categories, no narrative beyond what was asked.
If your record-keeping is digital, exports from your accounting system carry more weight when they arrive alongside the underlying source documents, not in place of them. A general ledger listing asserts a number; an invoice proves it.
The mechanics matter too. Submit through CRA's online portal — My Business Account for corporate matters, or through your representative — quoting the case or reference number so the documents land on the right desk; keep a complete copy of everything you send and a note of the date. Never mail originals. If you genuinely cannot assemble the documents by the deadline, call the number on the letter before the date and ask for an extension — CRA routinely grants reasonable ones, but only to people who ask in advance. And if the letter is about a return your previous accountant prepared and you cannot reconstruct what they claimed, that is a solvable problem we see often; the path through it is covered in what happens when a previous accountant made a tax error.
Once authorized as your representative, a CPA can see the review in your CRA account, speak to the reviewer directly, and file the response for you. For a straightforward review that is a small, defined piece of work — the kind our Quick Support clients hand over in a single message.
If something really is wrong: corrections, penalties and interest
Sometimes the review is right — the receipt does not exist, the claim was overstated, or income was missed. The worst response is to defend the indefensible; the best is to correct it cleanly and contain the cost. A review that ends in reassessment means the tax changes, and interest applies from the original balance-due date at CRA's prescribed rate, compounded daily — which is why speed matters even when you know you owe. Penalties layer on top in narrower cases: repeated failures to report income, or amounts CRA considers were misstated knowingly or through gross negligence.
If you find the error yourself, you have options the reassessment does not offer. A correction can be filed — an adjustment to the return, or an amended slip or schedule — and where amounts were never reported at all, the Voluntary Disclosures Program can provide penalty relief when you come forward before CRA starts asking about that issue. A review letter about one item does not necessarily close the voluntary door on unrelated items, but the timing rules are technical and the window closes fast, so take advice before deciding what to disclose and how. The mechanics for the most common version of this situation are set out in how to correct unreported investment income. If the reassessment lands and you disagree with it, you are not stuck either: a notice of objection filed within 90 days puts the dispute in front of CRA's appeals branch.
Interest is the quiet cost in all of this, because it accrues whether or not anyone has decided anything. If a reassessment looks likely and the amount is clear, paying the undisputed portion stops interest on what you pay while the dispute continues; if the review resolves in your favour, overpayments come back with refund interest. Treating the interest clock as part of the strategy, rather than an afterthought, is one of the cheapest habits in tax.
Make the next letter boring: retention and a compliance calendar
Reviews are only stressful when the documents are scattered. The retention rule is six years from the end of the tax year the records relate to, and CRA accepts organized digital copies — so the winning habit is filing support at the moment a claim is made, not reconstructing it under deadline years later. Every meaningful number on a return should have a folder behind it: the invoices behind the expense categories, the logs behind vehicle claims, the agreements behind management fees and rent, the statements behind interest and carrying charges.
For an owner-managed Ontario corporation, the calendar typically carries the T2 filing and balance-due dates for the corporate year-end, GST/HST filing and remittance dates, payroll remittances and the February T4 season, T5s for any shareholder dividends, corporate instalments, and the owners' personal filing dates — because CRA reviews the household as well as the company.
The second habit is a compliance calendar: every filing, instalment, remittance and renewal for the corporation and its owners on one dated list, owned by one person. Businesses that run one almost never receive the avoidable letters — the matching-program mail caused by a missed slip, the instalment interest, the late remittance penalty — and they answer the unavoidable ones in days because nothing has to be hunted down. When we onboard a new client, building this is part of the first month's work: we rebuild the support files for open years, take over CRA correspondence as representative, and set the calendar so reviews become routine correspondence rather than a fire drill.
What changes the answer, and when to bring in a CPA
Five facts decide how much attention a review letter deserves. Which program sent it — a matching letter about one slip is a different day than a corporate desk review of a six-figure expense category. Whether the claim is solid — documented claims get defended, doubtful ones get corrected. The dollars at stake, including interest that is already running. Whether the same issue repeats across other years, because a disallowance in one year invites the same question about its neighbours. And who prepared the return — if the answers live with an accountant you have left, or one who has stopped responding, the review is often the moment owners change firms.
Handle a review yourself when it is a single documented item and the folder is already in order. Bring in a CPA when the dollars are material, the documents are incomplete, the issue repeats across years, or the letter is the second one on the same file — escalation is exactly the wrong time to be learning the process. We provide CRA support and corporate compliance for Ontario businesses as part of CRA support: representative authorization, the response package, any corrections, and the retention system that keeps the next letter small. A review handled well usually ends with a one-line letter saying no changes were made. That is the goal, and it is a very achievable one.
