For most small business owners, GST/HST is the first piece of the tax system they have to deal with on a recurring basis — long before corporate tax planning or year-end financial statements enter the picture. And yet it’s also one of the most commonly misunderstood. As a CPA, the two questions I’m asked most often are some version of “Do I need to charge tax yet?” and “How often do I have to file?” Both have clear answers once you understand the rules. This guide walks through the registration threshold, the timing rules that trip people up, when voluntary registration makes sense, and how the filing process works once you’re in the system.
The $30,000 Small Supplier Threshold
The starting point for every business is the small supplier rule. If your total worldwide revenue from taxable supplies — across all your business activities, plus those of any associated businesses — stays at $30,000 or less, you are a small supplier and you are not required to register for GST/HST. You don’t charge it, you don’t file returns, and you don’t remit anything.
A few details matter here. The $30,000 figure is based on taxable supplies, which includes both regular taxable sales and zero-rated sales (more on that distinction below). It does not include exempt supplies such as long-term residential rent or most health-care services, and it excludes the sale of capital property. So a landlord earning $40,000 in residential rent is not over the threshold, because that rent is exempt. Counting it would lead to registering unnecessarily.
There’s also a higher $50,000 threshold for public service bodies (charities, non-profits, municipalities, and similar organizations), and charities have additional special rules. And certain businesses must register regardless of revenue: taxi and commercial ride-sharing operators (think Uber and Lyft drivers) must register from their very first dollar, with no small-supplier exemption.
The Timing Rules That Catch People Off Guard
This is where I see the most expensive mistakes, so it’s worth being precise. The CRA does not measure the threshold over a calendar year. It uses a rolling test based on calendar quarters, and there are two distinct ways you can cross it.
Scenario one — you exceed $30,000 in a single calendar quarter. The moment a single sale pushes your quarterly total over $30,000, you immediately cease to be a small supplier. Your effective date of registration is that day, and — critically — you must charge GST/HST on the very sale that put you over the line. You then have 29 days from that date to register.
Scenario two — you exceed $30,000 over four (or fewer) consecutive calendar quarters, but not in any single quarter. This is the more common path for steadily growing businesses. Here you remain a small supplier through those four quarters and for one additional month. You cease to be a small supplier at the end of that following month, and you have 29 days to register from your first taxable sale after that point.
The danger in the second scenario is that the threshold creeps up on you. A freelancer billing $8,000 a quarter across several clients can cross $30,000 midway through their fourth quarter without ever having a single big invoice. I’ve seen consultants operate for a year or more, unaware they’d blown past the threshold months earlier.
The consequences of registering late are real, and they fall on you, not your customers. If you should have been charging GST/HST and weren’t, the CRA can still assess the tax you ought to have collected — which means remitting it out of your own pocket, on revenue where you never billed the tax to begin with. On a year of unregistered consulting income, that can easily run into several thousand dollars, plus interest and potential penalties. The single best protection is keeping your bookkeeping current so you know in real time where your rolling revenue stands.
Should You Register Voluntarily?
Even if you’re comfortably under $30,000, you’re allowed to register voluntarily — and for many businesses, it’s the smarter move. The main reason is Input Tax Credits (ITCs). Once registered, you can recover the GST/HST you pay on legitimate business expenses by claiming it back on your return. If you’re spending heavily on equipment, inventory, software, or professional fees in your early days, those credits can meaningfully reduce your costs.
Voluntary registration tends to make sense in a few situations: you have significant start-up or capital expenses and want to recover the tax on them; your customers are primarily other GST/HST-registered businesses who simply claim the tax back themselves, so charging it costs them nothing; or you want the credibility that comes with being registered, since some clients expect their vendors to have a GST/HST number.
It’s not free of obligations, though. The day you register voluntarily, you take on every responsibility a mandatory registrant has — you must charge tax on all taxable sales and file returns on schedule, even while your revenue is still modest. The decision is worth modelling out: if you sell mainly to individual consumers who can’t recover the tax, adding GST/HST to your prices can make you less competitive, and the ITC savings may not outweigh the added cost and administrative burden. This is a good conversation to have with your accountant before you commit.
One practical tip: when you register voluntarily, your effective date can generally be backdated up to 30 days, which lets you claim ITCs on purchases made in that short window. If you’ve just made meaningful pre-registration purchases, that small bit of backdating is worth asking about.
How to Register
As of November 3, 2025, the CRA no longer accepts GST/HST registrations by phone. Registration is now done online through Business Registration Online (BRO), with mail registration via Form RC1 still available for situations the online portal can’t handle.
If you don’t yet have a Business Number (BN), BRO will issue your BN and your GST/HST program account (the “RT” account) in the same session. If you’re already incorporated, you almost certainly have a BN with a corporate income tax account attached, and you simply add the GST/HST account to it. Either way, have your legal business name, business address, a description of your activities, your fiscal year-end, and your estimated annual revenue ready. Online registrations typically process within a few business days.
Taxable, Zero-Rated, and Exempt: Know the Difference
Before getting into filing, it’s worth pinning down three categories, because they determine both what you charge and what you can recover.
Taxable supplies are the default — most goods and services, taxed at the applicable GST or HST rate. Zero-rated supplies are technically taxable but at a rate of 0%; you don’t charge tax to the customer, but you can still claim ITCs on related expenses. Basic groceries, prescription drugs, and most exports fall here. Exempt supplies are outside the system entirely: you charge no tax, and you cannot claim ITCs on related costs. Long-term residential rent, most health and dental services, childcare, and most financial services are exempt. Misclassifying an exempt supply as zero-rated (or vice versa) is a common and costly error, because it changes whether you can recover input tax.
A quick word on rates: GST is 5% nationwide. In the harmonized provinces, a single HST applies — 13% in Ontario, 15% in New Brunswick, Newfoundland and Labrador, and Prince Edward Island, and 14% in Nova Scotia following its rate reduction on April 1, 2025. The remaining provinces charge 5% GST alongside a separate provincial sales tax (or Quebec’s QST, administered by Revenu Québec). Which rate you charge is governed by “place of supply” rules — generally where goods are delivered, or the customer’s location for services.
Filing: Reporting Periods and Deadlines
Once registered, the CRA assigns you a reporting period — how often you file — based on your annual taxable supplies:
- $1.5 million or less: assigned annual filing (you may elect more frequent)
- More than $1.5 million up to $6 million: assigned quarterly (you may elect monthly)
- More than $6 million: monthly, with no option for anything less frequent
A useful principle: you can always elect to file more frequently than your assigned period, but never less. Most new and small businesses start as annual filers.
The deadlines follow from your reporting period. Monthly and quarterly filers must file the return and pay any balance owing within one month after the end of the period — so a quarter ending March 31 is due April 30. Annual filersgenerally have three months after their fiscal year-end to file and pay; a corporation with a December 31 year-end is due March 31.
The important exception — and one of the most misunderstood rules in the whole system — is for self-employed individuals who file annually and have a December 31 year-end. Their GST/HST return isn’t due until June 15, but any balance owing must still be paid by April 30. The split mirrors the personal income tax deadlines, and people regularly get caught paying interest because they assumed the payment deadline matched the June filing date. It doesn’t.
Two more points worth knowing. First, even annual filers may have to make quarterly instalment payments during the year if their net tax for the year is $3,000 or more. Second, electronic filing is now mandatory for virtually all registrants, and the CRA charges a penalty for failing to file electronically — so paper returns are effectively a thing of the past for most businesses.
Choosing Your Filing Frequency Strategically
Because you can elect a more frequent period, filing frequency can actually be a cash-flow tool. If your business consistently generates refunds — common for exporters with zero-rated sales, or businesses in a capital-intensive growth phase where ITCs exceed tax collected — filing monthly gets that money back into your hands twelve times a year instead of once. Conversely, if you typically owe money and prefer to minimize administrative work, annual filing keeps things simple, as long as you’re disciplined about setting aside the tax you collect rather than treating it as cash flow.
The Bottom Line
GST/HST is entirely manageable once the rules are clear: you’re a small supplier until your rolling taxable revenue crosses $30,000, at which point you have 29 days to register and must start charging tax immediately. Voluntary registration can pay off when you have real expenses to recover or sell mainly to other registered businesses. After registering, your filing frequency follows your revenue, and the deadlines flow from there — with that April 30 payment trap waiting for self-employed annual filers.
The most valuable habit any growing business can build is keeping its books current, so you always know where your rolling revenue sits and you’re never surprised by a threshold you crossed months ago. If you’re approaching $30,000, weighing voluntary registration, or simply want to set up your accounting to handle GST/HST cleanly from the start, a short conversation with your CPA before you need one is time well spent.
Disclaimer
The information discussed in this article is general in nature and should not be construed as any sort of advice. If you have any particular questions regarding your personal tax situation, please reach out to sandeep@multanitax.ca.
Photo by Jakub Żerdzicki on Unsplash
