"You don't need to charge GST until you hit $30,000." It's the single most repeated — and most misunderstood — piece of tax advice in Canadian small business. The number is right. Almost everything people assume about how it's measured is wrong.
Misreading this rule is expensive in a specific way: if you should have been charging tax and weren't, the CRA can still come after the tax you failed to collect. You can't always go back to a client a year later and ask for an extra 13%. So it comes out of your pocket.
- You're a "small supplier" — and exempt from registering — only while your worldwide taxable revenue stays at or under $30,000. The test is measured over four consecutive calendar quarters on a rolling basis, not per calendar year.
- The moment you exceed $30,000 in a single calendar quarter, you stop being a small supplier immediately — and you must charge GST/HST on the sale that put you over the line, not just on future sales.
- If you exceed it gradually over four quarters, you have a one-month grace period, then must register and start charging.
- The rate you charge is the customer's province, not yours — 5% GST in Alberta and most of the West, 13–15% HST in Ontario and Atlantic Canada. In Quebec you also deal with QST through Revenu Québec.
- Registering isn't only a burden — it lets you claim back the GST/HST you pay on business purchases (input tax credits). For some businesses, registering voluntarily before $30,000 actually puts money back in your pocket.
Read on for how the rolling test works, the two ways you can cross the line, the Quebec twist, and when to register early on purpose.
What "small supplier" actually means
Under Canada's Excise Tax Act, you don't have to register for or charge GST/HST as long as you qualify as a small supplier. You're a small supplier as long as your total worldwide taxable supplies — essentially your revenue from taxable sales of goods and services, including zero-rated sales, across you and any associated businesses — do not exceed $30,000.
Two things trip people up immediately:
- It's revenue, not profit. The $30,000 is measured on what you bill, before expenses.
- It's not a calendar-year test. It's measured over any four consecutive calendar quarters, rolling forward each quarter.
Source: Excise Tax Act subsection 148(1) (the small-supplier threshold) and section 240 (who must register); CRA, When to register for and start charging the GST/HST.
The two ways you cross the line
There isn't one threshold test — there are two, and they have different consequences. This is the heart of the confusion.
1. You blow past it in a single quarter
If your taxable revenue in one calendar quarter exceeds $30,000, you immediately stop being a small supplier. Your effective date of registration is the date of the sale that pushed you over — and you must charge GST/HST on that sale, not just on the next one. There's no grace period in this scenario.
2. You exceed it gradually over four quarters
If no single quarter tops $30,000 but your total over four consecutive calendar quarters does, you remain a small supplier for one more month. You must register by the end of the month following the quarter in which you crossed the cumulative total, and start charging from your registration date.
You charge based on your customer's province
Once you're registered, the rate isn't based on where you are — it's based on where your customer is (the "place of supply"). That means 5% GST in Alberta, BC, Saskatchewan, Manitoba and the territories; 13% HST in Ontario; and 15% HST in the Atlantic provinces. A solo consultant in Calgary billing an Ontario client charges 13%, not 5%. Getting the rate wrong is its own common error.
If you operate in Quebec: GST and QST
Quebec runs its own sales tax — the QST — administered by Revenu Québec, which also administers the GST within the province. The small-supplier concept mirrors the federal $30,000 test, but you generally register for and report both taxes through Revenu Québec. There are also specific activities (selling fuel, tobacco, alcohol, new tires, or road vehicles) that force QST registration regardless of the $30,000 threshold. If you do business in Quebec, treat it as two taxes, not one.
Source: Revenu Québec, Registering for the GST and QST and Details Concerning Small Suppliers. The QST small-supplier threshold mirrors the federal $30,000 test, with specific exceptions requiring mandatory registration.
Why registering early can actually pay
Registration is usually framed as a burden — more filing, more admin, charging your customers more. But there's a flip side: once you're registered, you can claim input tax credits (ITCs) — the GST/HST you pay on your own business purchases comes back to you.
That changes the math in two situations:
You have real startup or input costs
Buying equipment, software, inventory, or paying for a lot of taxable services? Registering — even voluntarily, under $30,000 — lets you recover the tax on all of it through ITCs.
Your customers are businesses
If you sell to other registered businesses, the GST/HST you charge them isn't a real cost to them — they claim it back. So charging it doesn't hurt your competitiveness, and you get to recover your own input tax.
When to wait
If you sell mostly to individual consumers who can't recover the tax, registering early makes you 5–15% more expensive to them with no offsetting benefit. Here, staying a small supplier as long as you qualify can be the right call.
The commitment
If you register voluntarily, you generally have to stay registered for at least one year. It's a deliberate decision, not something to toggle on and off.
A few traps that catch people
- The threshold counts associated businesses — you can't split revenue across two related entities to each stay under $30,000.
- "I'll register later" can mean uncollected tax. If you crossed the line months ago, you may owe tax on sales where you never charged it — and may not be able to recover it from those customers.
- Once registered, you have to file — monthly, quarterly, or annually — even for periods with no sales. Missed returns attract penalties.
- Zero-rated sales count toward the threshold (they're taxable at 0%), but truly exempt supplies generally don't.
Knowing exactly where your rolling revenue sits — and registering at the right moment, not months late — is the kind of thing a bookkeeper watching your numbers catches automatically. That's part of what's included in every CDL plan, and you can estimate the cost in about a minute.
Know your number before it crosses the line
The $30,000 threshold isn't complicated once you understand two things: it's measured on a rolling four-quarter basis, and crossing it can make you a registrant on the spot. The businesses that get burned are the ones who treat it as a once-a-year calendar check and discover, too late, that they should have been charging tax months ago.
And registration isn't always something to delay. If you have meaningful input costs or sell to other businesses, registering early can put money back in your pocket. The right answer depends on who your customers are — which is exactly the conversation worth having before you cross the line, not after.
The wedding that triggered a tax bill
Meet Amara, a wedding photographer in Winnipeg. For her first couple of years she stayed comfortably under $30,000 and never charged GST — she knew about "the $30,000 rule" and figured she had room. Then one summer everything clicked at once: a single busy quarter with eight weddings pushed her past $30,000 in those three months alone.
Amara kept invoicing without GST, assuming the threshold reset each calendar year and she'd deal with it "next year." But exceeding $30,000 in a single quarter made her a registrant immediately — and she owed GST starting with the very wedding that put her over, and every booking after it. She can't realistically go back to a dozen brides months later and ask for an extra 5%, so that GST comes straight out of her own pocket.
She thought she had until next year. She actually owed GST that same week.
What should have happened: watching her rolling four-quarter revenue would have flagged the crossing the moment it happened, so she could register and start charging on the next invoice — not discover it at tax time.
Not sure if you've crossed the $30,000 line — or whether you should register early?
A 20-minute call is usually enough to figure out where you stand and whether registering helps or hurts you.
Book a Free 20-Minute CallThis article is for informational purposes only and does not constitute tax advice. GST/HST and QST rules, rates, and thresholds change and depend on your situation, your customers' locations, and the nature of your supplies. Consult a qualified professional before deciding when and how to register.
Primary sources, linked so you can read and interpret them yourself. Legislative links open on the official Justice Laws Website; agency links open on Government of Canada and Revenu Québec websites.
- Excise Tax Act (Canada), Justice Laws Website: section 148 (the "small supplier" $30,000 threshold); section 240 (requirement to register)
- CRA — When to register for and start charging the GST/HST
- CRA — Register voluntarily for a GST/HST account
- CRA — Register for a GST/HST account
- Revenu Québec — Registering for the GST and QST
- Revenu Québec — Details Concerning Small Suppliers
- Related reading: Employee or Contractor?, Should You Incorporate?, and Writing Off Your Home Office