What triggers a CRA audit and how do I prepare?

The most common triggers

The CRA runs automated comparisons against industry benchmarks, so a business with expenses, margins, or a refund pattern well outside the normal range for its sector is more likely to be flagged, even with nothing wrong. Repeated years of reported losses, especially in a business that keeps operating and growing anyway, draws attention because it looks inconsistent on paper. Large or repeated HST refund claims get closer scrutiny than a typical remittance, since refunds are paid out before full verification.

Cash-intensive businesses, restaurants, salons, contractors paid in cash, are audited more often industry-wide because cash is easier to underreport. Real estate flips reported as capital gains rather than business income are a specific, well-known audit focus given how often the CRA disagrees with that characterization. A T1135 that does not match other information the CRA already has, foreign income reported elsewhere, or bank and brokerage data received directly, is another common flag. Occasional triggers include informant tips submitted through the CRA's leads program, and increasingly, data the CRA receives directly from payment platforms, ride-share and delivery apps, and other third parties.

Most of these triggers relate to patterns, not a single number in isolation. A business can have a legitimate reason for a loss, a large refund, or an outlier expense in any given year, and most of those situations never lead to an audit at all. What tends to draw a closer look is a pattern that persists across several years without an obvious explanation on file. A taxpayer who spots and corrects a mistake before the CRA does can often address it through the Voluntary Disclosures Program instead of waiting to see whether it turns into a full audit.

How the audit process typically unfolds

Most audits begin with a letter identifying the years and the specific issue or return under review, not a surprise visit. The letter usually sets a scope, a particular expense category, a specific credit claimed, or a full-return review, and a deadline to respond. Timelines vary by complexity; a narrow issue can close in weeks, while a full business audit can run for months, with the CRA requesting additional documents as the review progresses.

It helps to read the letter carefully for exactly what is being asked before responding, since answering a narrower question than what was actually requested, or a broader one, both tend to slow things down.

It is also worth confirming the deadline in the letter and requesting an extension early if more time is genuinely needed to gather records, rather than letting the date pass. Auditors are generally more accommodating to a taxpayer who communicates proactively about a realistic timeline than to one who simply goes quiet until the deadline has already lapsed.

Your rights and representation

A taxpayer has the right to know the scope of the audit, to be treated professionally, and to have a representative deal with the CRA on their behalf. Authorizing an accountant to speak for you requires filing form AUT-01 (or, for a business, the equivalent authorization through My Business Account), which lets the CRA discuss and correspond directly with your representative instead of only with you. Having representation in place before the audit starts, not after it becomes stressful, tends to keep communication cleaner and more consistent, and it means every phone call or letter goes through someone who deals with the CRA routinely rather than someone experiencing the process for the first time.

Getting records ready without over-sharing

The right approach is to organize exactly what the letter requests, invoices, bank statements, contracts, mileage logs, whatever applies to the specific issue, and provide that cleanly. It is generally not advisable to volunteer additional records, unrelated years, or unprompted explanations beyond what was asked, since that can expand the scope of the review into areas that were not originally in question. If a request is unclear, it is reasonable to ask the auditor to clarify exactly what they need before assembling a large volume of documents.

Keeping records organized by category, rather than handing over a single unsorted folder of everything, also tends to shorten the review. An auditor working through a clearly labelled set of invoices or bank statements can usually close a specific question faster than one who has to sort through unrelated material first to find what was actually requested.

If you disagree with the result

If an audit results in a reassessment you believe is wrong, the next step is a formal Notice of Objection, which puts the file in front of the CRA's Appeals division for an independent review, separate from the auditor who issued the original reassessment. There are firm deadlines for filing an objection, so it is worth acting on a reassessment notice promptly rather than letting the window close. If Appeals does not resolve the disagreement, the next step is the Tax Court of Canada, though most disputes are settled well before that stage is ever needed.

How we support clients through an audit

Through our tax services, we act as the authorized representative on file, organize the specific records requested, and manage correspondence with the auditor directly, so the client is not fielding CRA calls personally in the middle of running their business. We also review the scope of each request before anything goes out, since staying inside the boundaries of what was actually asked is often what keeps a narrow audit narrow. Our post on common CRA audit red flags for small businesses goes deeper on the specific patterns auditors look for by industry, which is worth a read even for a business that has never been audited before.