GST, QST & HST Filing

When you have to register for GST/HST and QST

You must register once your taxable supplies exceed $30,000 over four consecutive calendar quarters. That is a rolling test, not a calendar-year one, and it counts worldwide taxable supplies of the business and its associates — not just the revenue you invoiced in Québec. Cross the threshold in a single quarter and you are required to register immediately; cross it over four quarters and you have a one-month grace period. Québec applies the same $30,000 test for QST. Registering before you have to is often the better call. A pre-revenue business that is buying equipment, paying for a build-out or running up professional fees is paying GST/QST it cannot recover until it registers. Voluntary registration turns those into recoverable input tax credits.

• Taxi, ride-share and most digital-platform operators must register from the first dollar
• Non-residents selling into Canada may have to register even without a Canadian office
• Associated companies share one $30,000 threshold — you cannot split revenue to stay under it
• Voluntary registration lets a start-up recover tax on pre-revenue spending

Why Québec files differently

Québec is the exception in Canada. For most registrants Revenu Québec — not the CRA — administers the federal GST alongside the provincial QST, so one agency, one account structure and usually one combined return covers both. That is genuinely simpler once it is set up, and a common source of errors before it is. Businesses that register federally first, or that move into Québec from another province, frequently end up with mismatched reporting periods, a QST account that was never opened, or returns filed to the wrong agency. QST is charged on the pre-GST amount, not on the GST — the two taxes are not compounded. On a $100 sale in Québec you charge $5.00 GST and $9.98 QST for a total of $114.98.

The Quick Method — and when it is worth electing

The Quick Method lets an eligible small business remit a reduced flat percentage of its GST/HST-included sales instead of tracking input tax credits on every purchase. Québec has an equivalent election for QST. Eligibility is capped at $400,000 in annual taxable supplies including GST/HST. The election generally pays off for service businesses with low taxable purchases — consultants, professionals, trades with little material cost — because they collect far more tax than they spend. It usually costs money for businesses that buy a lot of taxable inputs: retailers, restaurants, anyone carrying inventory or buying equipment. It is not a permanent decision, but it is not one to guess at either. We run the comparison on your actual numbers before electing.

Input tax credits: what you can actually claim

An input tax credit recovers the GST/HST you paid on purchases made to produce taxable supplies. The QST equivalent is called an input tax refund. Claimed properly they are the difference between sales tax being a pass-through and sales tax being a cost. The two things that get claims denied on audit are documentation and apportionment. You need a supplier invoice carrying the supplier's registration number to support a claim — a credit card statement is not enough. And where an expense is part business and part personal, or supports both taxable and exempt supplies, only the business or taxable portion is recoverable. There are also hard restrictions worth knowing: club memberships and most passenger-vehicle costs above the capital limit are not claimable, and meals and entertainment are generally restricted to 50%.

• Keep supplier invoices showing the GST/QST registration number, not just receipts
• Apportion mixed-use expenses — home office, vehicle, phone — to the business share
• Meals and entertainment ITCs are generally limited to 50%
• Late claims are still available, but the window to claim is limited — do not sit on them

PST in British Columbia, Saskatchewan and Manitoba

Three provinces run a provincial sales tax entirely separate from GST, with their own registration, their own returns and their own rules about what is taxable. British Columbia charges PST at 7%, Saskatchewan at 6%, and Manitoba levies RST at 7%. These are not harmonized, which means a business selling into them can have a GST/HST obligation to the CRA and a completely independent PST obligation to the province. Registration is often triggered by selling into the province rather than by having an office there, so a Montréal business shipping to Vancouver customers can end up registered in British Columbia. Unlike GST, PST is generally not recoverable by the purchaser — it is a cost, not a flow-through. Getting the taxability question right at the front end matters more than it does with GST.

What late or missed filings cost

A late GST/HST return carries a penalty calculated from the amount owing and the number of months it is overdue, and interest runs on the balance from the day after it was due. Québec applies its own penalty and interest to a late QST return, so a late combined filing is penalised twice. The bigger risk is not filing at all. The CRA and Revenu Québec can raise an arbitrary assessment based on their own estimate of your sales, and that estimate is not built to be generous. Once assessed, the burden is on you to displace it with real numbers. If you have returns outstanding, the Voluntary Disclosures Program may reduce or eliminate penalties — but only if you come forward before the agency contacts you about them. That window closes the moment they write to you.