Goods and Services Tax (GST) in Canada: The Practical Guide (Rates, Registration, ITCs, Deadlines, and CRA Audit Traps)
GST looks simple on paper: 5% federal tax on most goods and services. In real life, GST/HST issues are one of the fastest ways businesses end up with CRA reassessments, denied refunds, penalties, and interest.
This guide covers:
- what GST is (and when it’s actually HST, not GST)
- the $30,000 “small supplier” trap
- taxable vs zero‑rated vs exempt (and why this matters for ITCs)
- how to charge, claim, file, and remit correctly
- the CRA’s most common audit pressure points
1. What GST Really Is
GST is a consumption tax that applies to most property and services supplied in (or imported into) Canada. Businesses generally act as the CRA’s “middleman”: they collect GST/HST on sales and can usually recover GST/HST paid on business expenses through input tax credits (ITCs).
2. GST vs HST: Why Your Province Isn’t the Whole Story
Canada has:
- GST (5%) in non-participating provinces/territories, and
- HST (combined federal + provincial rates) in participating provinces.
3. The 3 Tax Statuses That Decide Almost Everything
Before you talk about “GST,” you need to classify the supply:
3.1 Taxable supplies
Most supplies are taxable at 5% GST or the applicable HST rate.
3.2 Zero-rated supplies
These are taxable at 0% (so you charge no GST/HST), but they still count as taxable supplies and typically still allow ITCs. Example: many basic groceries are zero-rated.
3.3 Exempt supplies
No GST/HST is charged, and ITCs are generally not available for costs related to exempt supplies.
This is where people get burned: “no tax to the customer” can mean zero‑rated (ITCs usually allowed) or exempt (ITCs usually denied). Getting this wrong can wipe out years of ITCs in an audit.
4. Do You Have to Register? The $30,000 Rule (With a Big Catch)
Most businesses register when they stop being a small supplier.
You generally must register if you make taxable supplies and you are not a small supplier.
There are generally two ways you can cross the $30,000 threshold:
- You exceed $30,000 in a single calendar quarter
You must charge GST/HST on the very supply that pushed you over $30,000, and your effective registration date is no later than that day. - You exceed $30,000 over the last four consecutive calendar quarters (but not in one quarter). You stop being a small supplier at the end of the month after the quarter you exceeded $30,000, and you must register and start charging from that point.
Special case – taxi and ride‑sharing drivers: If you supply taxable passenger transportation as a self‑employed taxi operator or commercial ride‑sharing driver, registration is mandatory even if you’re under $30,000.
5. What Happens If You Should Have Registered… But Didn’t?
This is the classic GST nightmare:
- You pass $30,000 and don’t register.
- You keep charging customers “normal prices” (no GST/HST line item).
- CRA audits and says: you should have been charging and remitting.
Result: the CRA can assess you for unremitted GST/HST, plus interest and penalties, and you may not be able to go back to customers to collect it.
6. Charging the Right Rate: The “Place of Supply” Problem
To charge the correct tax, you need two answers:
- What type of supply is it? (taxable, zero‑rated, exempt)
- Where is it made? (place of supply determines the GST vs HST rate)
7. ITCs: How Businesses Get GST/HST Back (And How CRA Denies Them)
If you’re registered, you can generally claim input tax credits (ITCs) for GST/HST paid or payable on purchases used in your commercial activities.
7.1 Documentation is non‑negotiable
CRA can deny ITCs if you can’t produce the required supporting info (for example, supplier name, date, amount, and – above certain thresholds – registration details).
7.2 Mixed-use businesses must apportion
If you have both commercial (taxable/zero‑rated) and non‑commercial/exempt activities, you may need to allocate GST/HST and claim only the portion related to commercial use.
7.3 New registrants: you may get ITCs on what you already own
When you register, you may be able to claim ITCs for certain inventory/capital property on hand at registration – but there are limits, and services used before registration are treated differently.
7.4 Record retention
You generally must keep GST/HST records for 6 years from the end of the year they relate to.
8. Filing and Paying GST/HST: Deadlines That Matter
Once registered, you must file a return every reporting period, even with no activity (a “nil return”).
8.1 Mandatory electronic filing
For reporting periods ending in 2024 and later, almost all registrants must file GST/HST returns electronically (charities and selected listed financial institutions are the main exceptions). Paper filing can trigger a penalty.
8.2 Filing & payment deadlines
- Monthly/quarterly filers: deadline is 1 month after the reporting period ends.
- Annual filers: deadlines depend on fiscal year-end and business income. For example, if your fiscal year-end is Dec 31 and you have business income, CRA lists Apr 30 (payment) and Jun 15 (filing).
8.3 Instalments (annual filers)
If you file annually and your prior-year net tax was $3,000 or more, you may need to make quarterly installment payments during the year.
9. The CRA Audit Traps That Cause the Most Damage
Here are the GST/HST issues that most commonly spiral:
- Missing the $30,000 threshold (especially the “single quarter” rule)
- Treating exempt supplies like zero-rated (or vice versa)
- Claiming ITCs without compliant invoices/records
- Charging the wrong rate because of place-of-supply confusion
- Filing late, skipping nil returns, or filing on paper when e-filing is mandatory
10. Two “GST Doesn’t Care” Situations: Directors and Trust Money
If you run a corporation, GST/HST can become personal.
CRA’s directors’ liability guidance explains that directors can be held personally liable for failures relating to GST/HST under section 323 of the Excise Tax Act, with a due diligence defence and other statutory requirements (including timing rules).
11. If You’ve Made Mistakes, Don’t Guess – Fix It Properly
If you suspect you should have registered, under-charged, over-claimed ITCs, or missed filings, the best approach is usually:
- quantify the exposure (period-by-period),
- get compliant going forward, and
- consider whether a voluntary disclosure is available before CRA contacts you.
12. When a Tax Lawyer Helps Most
GST/HST problems are rarely just “paperwork.” Legal help matters most when:
- you’re facing a CRA audit or reassessment,
- GST is tied to real estate, platforms, or cross-border issues,
- penalties/interest are compounding, or
- director’s liability is on the table.