GST/HST Audit Readiness Checklist for Canadian Firms
- Published
- Reading time
- 9 min
- Written by
- SpidNums
GST/HST audit readiness means every filed return traces to its working papers on request: reported sales reconcile to the ledger, input tax credits carry documents naming the supplier and the tax charged, and place-of-supply decisions are recorded for out-of-province sales. Firms that maintain this per period treat an audit letter as retrieval, not reconstruction.
What does a GST/HST audit actually look at?
Whether the returns you filed match the records you kept. An auditor typically works three angles: were all taxable sales reported, are the input tax credits claimed properly documented, and was the right rate applied given where each supply was made. Everything on this checklist serves one of those three.
Refund-claiming returns are commonly reviewed before the refund is paid, and unusual swings between periods invite questions. Neither means anything is wrong — but both mean the supporting file should exist before the question arrives, not be assembled after it.
The ITC documentation test most files fail
An input tax credit is only as good as its paper. The CRA's documentation requirements scale with the size of the purchase — larger amounts need more detail, including the supplier's name and GST/HST registration number — and a credit card statement alone does not meet them.
The practical habit is capturing the actual invoice at the time of entry, not at audit time. Suppliers disappear, portals purge history, and a missing invoice years later usually means a denied credit plus interest. Confirm the current documentation thresholds on canada.ca rather than trusting memory — they have changed over the years.
Reconcile each filed return to the books
Every filed period should keep a one-page reconciliation: ledger sales to the sales reported, tax collected per the books to the tax remitted, ITCs claimed to the expense detail — with differences explained. If that page exists for every period, an audit is retrieval rather than reconstruction.
Differences are normal — timing, bad-debt adjustments, restricted credits on meals and entertainment — and a noted difference is a non-issue. An unexplained difference found first by the auditor is where reviews widen.
Record place-of-supply decisions when you make them
A supplier selling across provinces has to decide which rate applies to each sale, and an auditor may test those decisions years later. Record the reasoning at invoicing time — the customer's province and the rule applied — because rates differ across HST provinces, GST-only provinces and Québec.
This matters most for services and digital sales, where the customer's location rather than the supplier's generally drives the rate. A short standing note per client or revenue stream covers most businesses; the point is that the decision is written down somewhere.
How long GST/HST records must be kept
As a general rule, records supporting a return must be kept for six years from the end of the year they relate to — and they must remain producible, because a subscription that lapsed with the data inside does not count as kept.
Confirm the current retention rule and its edge cases on canada.ca, since periods under objection or appeal carry longer obligations. For firms, the operational question is where the records live and who can retrieve a given period in minutes.
Make readiness a per-period habit
Audit readiness is cheapest at filing time. Append three recurring steps to every GST/HST engagement — attach the reconciliation, spot-check ITC documentation, note anything unusual about the period — and the audit file builds itself as a by-product of the work.
This is cadence work, which is why it belongs in the system that drives the filings. In SpidNums, a client's GST/HST service runs on their assigned reporting period from the Services catalogue, and the readiness steps ride along as ordered tasks in Task Master — done every period because they are on the board, not because someone remembered.
When the letter arrives anyway
Respond by the stated deadline, confirm exactly what is being asked, and send precisely that — organised, labelled by period, nothing extra. A prompt, complete first response settles many reviews before they widen into anything larger.
Log the correspondence like any other dated obligation: who is handling it, what was sent, when the response went out. Firms with a standing process for CRA letters treat an audit notice as a workflow, not an emergency — a separate discipline worth building before it is needed.
Frequently asked questions
What records does the CRA ask for in a GST/HST audit?
Typically the sales records and invoices behind reported revenue, the purchase invoices supporting input tax credits, bank statements, the ledger itself, and anything explaining rate decisions on sales across provinces. The common thread is traceability: the auditor wants to walk from the filed return down to source documents. A period-by-period file with a reconciliation on top answers most requests directly.
How long do you need to keep GST/HST records?
Generally six years from the end of the year the records relate to, and they must stay producible on request — data locked inside a cancelled software subscription does not qualify. Longer obligations can apply, for example while an objection or appeal is open, so confirm the current rule on canada.ca before setting a firm-wide retention policy.
Can you claim an input tax credit without an invoice?
It is risky. The CRA's documentation requirements specify what must support a claimed ITC, with more detail required as the purchase amount rises — including the supplier's name and registration number at higher tiers — and a bank or card statement alone generally falls short. The safe practice is capturing the invoice when the expense is recorded, because reconstructing documentation years later often fails.
What is the difference between a CRA review and a full audit?
A review is usually a targeted request to support specific amounts on a filed return — often before a refund is paid — while an audit is a broader examination of the books and records behind one or more periods. The preparation is identical: reconciled returns, documented ITCs and retrievable records answer both, and a clean response to a review often ends the matter there.
Keep reading
Scenarios
Go deeper
Start running a tidier, deadline-proof practice.
Set up your firm in minutes. No credit card to start.