Updated Checked by the Tax-Services.ca editorial team How we check
For a GST/HST audit, the CRA wants the records behind every figure on your returns: sales and purchase invoices, plus everything else that ties your business activity to the tax you reported. You need to keep them for six years from the end of the year they relate to.
What records will an auditor ask to see?
The CRA’s audit booklet lists ledgers, invoices and bank statements as the usual business records, on paper or electronic. In practice, think of it as a chain. A sale shows up in your books, the books match the bank deposit, and the deposit matches the invoice. Break any link and the auditor starts asking questions.
| Record | What it backs up |
|---|---|
| Sales invoices and receipts | GST/HST you collected and reported |
| Purchase invoices from suppliers | Input tax credits you claimed |
| Ledgers and journals | The totals on each return |
| Bank statements | That the money moved when the books say it did |
| Copies of filed returns | What you actually told the CRA |
| Contracts and rental agreements | Why a supply was taxed, zero-rated or exempt |
The purchase side gets the closest look, since that’s where money leaves the government’s pocket. The CRA says supplier invoices have to carry the right information to support a credit. A credit with no proper invoice behind it is the classic adjustment.
How long do you have to keep GST/HST records?
Usually six years from the end of the year they relate to. Want to throw something out sooner? You need to send a written request to your tax services office and wait for a yes. Shredding on your own schedule can get you in trouble.
If you’ve fallen behind on filing, the clock is messier. A return for a period that ended more than six years ago still has to be filed, and the records behind it still have to exist.
What should you do when the audit letter arrives?
The CRA starts by mail or phone. Read the letter for the periods and the taxes covered. Then make a list of what’s asked and pull it together in date order before anyone calls back.
Some practical points from the CRA’s own guidance. Audits can happen at your business, at your representative’s office or at a CRA office. Auditors aren’t allowed to take records by email, so ask how to send files through the CRA’s secure online services. Answer what’s asked and keep copies of everything you hand over.
How long it takes depends on how tidy your records are, how wide the audit is and how quickly you respond. A clean set of files shortens it.
What does a small mistake cost? A worked example
Say you bought $2,000 of equipment in Nova Scotia. At 14% HST the tax is $280.00, and the total is $2,280.00. You claimed the $280 as an input tax credit, but the supplier’s invoice went missing.
The auditor can’t tie the claim to a document, so the $280 is at risk. Multiply that by a few dozen invoices over three years and the bill gets real quickly. You can check your own tax figures with the GST/HST calculator, or work backwards from a total with the reverse HST calculator. If you’re tracking margins alongside tax, the profit margin calculator shows what a disallowed credit does to your profit.
Mistakes that make audits harder
Mixing personal and business spending in one account is the big one. Keep them apart.
Others: keeping only a bank statement with no invoice, storing electronic records in a format nobody can open now, and losing the accounting file when you change software. Electronic records have to stay readable for the full retention period, and having a paper copy doesn’t excuse you from keeping the electronic one.
Also, a return that you filed electronically doesn’t come with receipts attached. You don’t send them in, but you must be able to produce them when asked. Keep a working copy of each return.
If the audit ends with more tax owing, you have the right to appeal through the CRA’s dispute process. Get the final letter and read what it says about the periods and amounts before you decide.
Where do these numbers come from?
Retention rules and audit steps come from the Canada Revenue Agency pages on GST/HST records and its audit booklet, and the Nova Scotia rate from the CRA’s rate information, all read in September 2026. This site is not connected with the CRA or any government body.
Frequently asked questions
How long must I keep GST/HST records?
Usually six years from the end of the year they relate to. To destroy records earlier, send a written request to your tax services office and wait for approval.
Can I send audit records to the auditor by email?
No. The CRA says auditors can't receive records by email, so ask how to use the CRA's secure online services.
Do I need paper copies if my books are electronic?
No, but the electronic records must stay readable for the full retention period, and you must be able to produce them when asked.
What if I lost a supplier invoice?
Ask the supplier for a copy. Without proper invoice information the input tax credit can be disallowed.
Can I appeal an audit result?
Yes. If the CRA reassesses you, you have the right to appeal through its dispute process.
- Dealing with the CRA: letters, audits and payments
Dealing with the CRA: what to do when a letter arrives, how a review differs from an audit, how My Account helps, and what to do if you can't pay
Information only. This page is general information, not tax, legal or accounting advice. Tax-Services.ca is an independent publisher: we don't prepare or file tax returns or offer tax services, and we have no connection with the CRA, Revenu Québec, any government or any company named on this page. Check the figures that matter with an official source or a qualified professional.