CRA audit triggers — what gets small businesses flagged

An audit letter from the CRA is nobody's idea of a good day — but audits aren't random bad luck as often as people think. The CRA uses data to flag returns that look unusual, and understanding what stands out helps you file cleanly and stay off the radar. Here's what actually draws attention.

How the CRA decides who to look at

The CRA runs your return through risk-assessment systems that compare it to industry norms and cross-check it against data it already holds — your slips, your GST/HST filings, information from customers and suppliers. Returns that sit far outside the expected pattern get a closer look. It's less “gotcha” and more “this doesn't match, let's ask.”

The common triggers

Claims out of line with your industry

If your expense ratios or margins look nothing like comparable businesses, that gap invites a question. Being different isn't wrong — but it should be explainable.

Repeated losses

A business that reports losses year after year while continuing to operate raises the question of whether it's a real commercial venture. One bad year is normal; a long pattern needs a clear story.

High or round-number deductions

Unusually large expenses relative to income — or suspiciously tidy round numbers — suggest estimates rather than records. Big home-office and vehicle claims are legitimate but frequently reviewed; claim a reasonable business-use share and keep the log.

Cash-heavy businesses

Industries where cash is common (restaurants, trades, personal services) get extra scrutiny because unreported income is harder to trace. Meticulous records are your friend here.

Mismatches

This is the easiest flag of all for the CRA to catch: your T-slips, your GST/HST returns and your income tax return should all tell the same story. When they don't, the system notices automatically. Clean, reconciled bookkeeping is what keeps them aligned.

How to stay audit-ready (without fear)

• Keep clean, reconciled books and every receipt.
• Make sure your slips, GST/HST and tax return agree.
• Claim reasonable, well-documented deductions — and be able to explain the unusual ones.
• File on time; late and amended returns draw attention.

What to do if you are audited

Don't panic — an audit isn't an accusation, and many are routine or even random. Respond promptly, provide organized records, and let your CPA deal with the CRA on your behalf. Owners who have clean books and a professional in their corner usually find it far less painful than they feared. That's a core part of our corporate tax service.

The bottom line

You can't make yourself audit-proof, but you can make an audit a non-event: accurate returns, matching data, reasonable claims and real records. File that way every year and the CRA has little reason to look twice. If a sales-tax review does land, our guide to what a GST/HST audit checks sets out the process and the records to have ready. If you'd rather not think about it at all, book a free consult and we'll handle it.

This article is general information for Canadian business owners and is current as of July 2026. It is not tax, legal or accounting advice, and it does not create a client relationship. Tax rules change and your situation is unique — please speak with a CPA before acting on anything here.

Two areas draw questions more often than the rest: salary paid to a spouse or family member, where reasonableness must be demonstrable, and home office expenses claimed through a corporation, where the mechanism differs from the personal claim most people know.

Most CRA contact stops well short of an audit. The usual first step is a letter asking for documents behind a single claim — see answering a CRA request for information. If the outcome still looks wrong to you, a notice of objection is the formal route, and it runs on a deadline.

Marketing costs that look large relative to revenue attract the same kind of attention, and the media rules there are easy to get wrong — our guide to advertising and promotion deductions sets out what is and is not claimable.