How to Prepare for a CRA Audit (From Someone Who Used to Run Them)
You open your mail and there it is. A letter from the Canada Revenue Agency letting you know your business has been selected for an audit. Your stomach drops, and your mind starts racing through every receipt you did not save and every HST return you filed in a rush.
Take a breath. We have been on both sides of this table. Before we started Better Books Canada, we worked in the CRA’s audit division, so we have been the person writing that letter. And we can tell you right now: most business owners make this way harder than it needs to be. Here is what actually happens during an audit, and how to come out clean.
What a CRA audit actually is
A CRA audit is a detailed review of your books and records to confirm that what you reported on your return matches what actually happened in your business. That is it. They are checking your math, your receipts, and your logic. The CRA is usually not trying to catch you committing fraud. Their risk assessment systems flagged something that looked unusual, and now an auditor needs to verify the numbers. If your instinct at that point is to ask a chatbot what to do, read can you trust AI for taxes first.
When we worked in the audit division, the returns that got flagged fastest were the ones with ratios that did not make sense. A restaurant claiming 200,000 dollars in food costs on 180,000 dollars in revenue. A consultant writing off 40,000 dollars in vehicle expenses. Numbers that stand out get looked at. Simple as that. Content businesses draw the same attention for the same reason, which is why we wrote a separate guide to content creator write offs in Canada.
What the CRA actually asks for
Once an auditor contacts you, they request specific documentation for the tax years under review. Here is what you should have ready.
Your financial records, meaning income statements, balance sheets, the general ledger, and bank statements. If you are on QuickBooks Online, you can pull most of this in minutes. Your source documents, meaning every receipt, invoice, and deposit slip that supports the numbers on your return. The CRA requires you to keep these for at least six years from the end of the tax year they relate to, and the full rule is on the CRA’s keeping records page. If you want the plain version, we wrote a whole guide on what records the CRA requires you to keep.
They will also ask for your HST and GST records, including your returns, input tax credit calculations, and the invoices behind every credit you claimed. This is one of the most common areas where audits find problems, which is why clean HST and GST tracking and filing matters all year, not just at filing time. Round it out with your payroll records and, if you claimed vehicle expenses, a mileage log showing business versus personal kilometres. Not “I think I drove about 70 percent for business.” An actual log, with dates and destinations.
The mistakes that make auditors suspicious
We have seen hundreds of audit files. Here is what makes an auditor dig deeper instead of wrapping things up quickly.
Missing receipts are the biggest one. If you claimed 8,000 dollars in advertising but can only produce 3,000 dollars in receipts, the auditor will not take your word for the other 5,000. They disallow it and add it back to your income.
Mixed personal and business expenses are a close second. When your personal groceries and business supplies flow through the same card, the auditor has to sort through every transaction, the audit takes longer, and longer audits tend to find more problems. The fix starts with separating your personal and business finances completely.
Round numbers everywhere are another tell. If every category is a tidy 5,000 or 10,000 dollars, it looks like you guessed instead of tracked. Real bookkeeping produces messy numbers like 4,837.22. It is also the trap when you are rebuilding books that are behind, because reconstructed records tend to come out too smooth. And no mileage log is the last big one. The CRA expects a log you kept throughout the year, not one written from memory after the letter arrives, and auditors can usually tell the difference.
How to prepare before the CRA ever contacts you
The best time to prepare for an audit is right now, before one ever happens. Here is the checklist.
Separate your business and personal finances with a dedicated account and credit card used only for business. This alone eliminates half the problems we see in audit files. Save every receipt, scanned or photographed, showing the date, vendor, amount, and what was purchased. Reconcile monthly so any discrepancy turns up now instead of during an audit, which is the heart of a good monthly financial review.
Keep a vehicle log with the date, destination, purpose, and kilometres for every business trip. Document the business purpose of meals, since the CRA lets you deduct 50 percent of business meals but wants to see who you met, why, and when. If you are not sure which expenses even qualify, our guide to what you can write off as a small business owner covers it. And file and pay on time, because a history of late filing is one of the signals the CRA uses to flag returns.
What happens during the audit
The auditor contacts you by mail or phone to schedule the review, tells you which tax years they are looking at, and lists the documents to prepare. If your records are electronic, and they should be, the auditor usually asks for the digital files first. That speeds things up and means less time at your location. We always preferred reviewing electronic records because it was faster for everyone.
The auditor compares your reported income and expenses against the source documents, checks that your HST was calculated correctly and your credits are supported, and reviews your bank deposits to confirm all income was reported. The agency already holds a great deal of that data, which is what makes automatic tax filing in Canada possible for simple personal returns. If everything ties out, you get a letter saying no adjustments are needed. If they find discrepancies, they issue a proposal letter outlining the changes, and you typically get 30 days to respond with more documentation before anything is finalized.
If you disagree with the results
You have the right to object. If the auditor proposes adjustments you think are wrong, talk to them first, because many issues get resolved just by providing more documentation or explaining the business context. If you still disagree after the audit is finalized, you can file a formal objection, which sends the file to a different team that looks at it fresh. You generally have 90 days from the date on your notice of reassessment to file, as the CRA explains on its file an objection page.
We have helped clients through both sides of this. The key is staying organized, responding promptly, and keeping it professional. Getting emotional or adversarial with the auditor never helps.
The bottom line
A CRA audit does not have to be a nightmare. Keep clean books, save your receipts, reconcile monthly, and document everything. If your records are solid, the audit is routine. The owners who panic are the ones who fell behind on their bookkeeping, and catching up later costs far more than staying current, which is worth weighing against how much a bookkeeper costs in Canada. The ones who shrug it off are the ones whose books are clean. Be the second one.
Frequently asked questions
What triggers a CRA audit?
Usually the CRA’s risk assessment system flags something unusual, like expenses that are high relative to revenue, ratios that do not fit your industry, or a history of late filing. Sometimes it is random. A flag is not an accusation, it just means an auditor needs to verify your numbers. We break the selection criteria down in full in our guide to what triggers a CRA audit.
How many years can the CRA audit?
Most reviews look at the past few tax years, and you must keep your records for at least six years from the end of the tax year they relate to. In cases of suspected fraud or misrepresentation, the CRA can go back further, which is one more reason to keep complete records.
What do auditors look for first?
Whether your source documents back up what you reported. Receipts and invoices that match your claimed expenses, valid invoices behind your HST credits, and all income showing up in your bank deposits. Missing receipts and mixed personal accounts are the fastest way to make an audit drag on. If you file under the quick method, expect the reviewer to test the remittance rate you used and whether you applied it to tax included sales.
Do I need a mileage log for vehicle expenses?
Yes. The CRA expects a log you kept through the year showing the date, destination, purpose, and kilometres for each business trip. A log reconstructed from memory after the audit letter arrives usually does not hold up.
How long do I have to dispute an audit result?
If the auditor proposes changes, you typically have 30 days to respond before they finalize. After a reassessment, you generally have 90 days from the date on the notice to file a formal objection, which sends your file to a separate CRA team for a fresh review.
Not sure your books would hold up?
If you are not sure whether your records would survive a CRA review, we are happy to take a look. Book a free consultation and we will tell you exactly where you stand.
Last updated: June 2026. Verify current rules and timelines against canada.ca, since CRA requirements can change.
