Get paid · GST
Do I need a GST number as a subcontractor?
General information for Saskatchewan and Alberta, checked November 14, 2026. It isn't tax, legal or accounting advice. Your situation may differ, so confirm with CRA, the Ministry of Finance or an accountant before you rely on it.
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Not until your taxable sales pass $30,000, either in a single calendar quarter or over the last four calendar quarters combined. Until then you're a "small supplier" and registering is optional. Once you pass it, you have to register and charge GST (5% in Saskatchewan and Alberta).
How the $30,000 test works
CRA looks at calendar quarters (Jan–Mar, Apr–Jun, Jul–Sep, Oct–Dec), not your tax year. The test counts taxable sales you and any associates made, not profit. (GST/HST Memorandum 2-2, Small suppliers)
| What happened | What it means | When you must start |
|---|---|---|
| You stay at or under $30,000 over four consecutive quarters | You're a small supplier. You don't have to register, but you can choose to. | Only if you choose to register voluntarily |
| You go over $30,000 in a single quarter | You stop being a small supplier right away. | Charge GST on the very sale that took you over, and register within 29 days of your effective registration date |
| You go over $30,000 across four quarters (but not in one) | You stop being a small supplier at the end of the month after the quarter you went over. | Register within 29 days of your effective registration date, and charge GST from that date |
Worked example
A new skid-steer and gravel-hauling sub starts billing in October:
| Quarter | Billed (before GST) | Running 4-quarter total |
|---|---|---|
| Oct–Dec | $12,000 | $12,000 |
| Jan–Mar | $6,000 | $18,000 |
| Apr–Jun | $14,000 | $32,000 |
No single quarter went over $30,000, but the four-quarter total did in Apr–Jun. Under CRA's rule, the sub stops being a small supplier at the end of July (the month after that quarter) and has to register within 29 days of the effective registration date. From that date on, every invoice carries 5% GST, and the effective date can be no later than the first sale made after July 31.
If the Apr–Jun quarter had been one $31,000 job, the single-quarter rule would apply instead, and GST would be due on that job's invoice.
Should you register before you have to?
Registering early has two upsides for an equipment business:
- Input tax credits. Registrants can recover the GST they pay on business costs such as fuel, maintenance and repairs, motor vehicle expenses and start-up costs. (CRA, Input tax credits) CRA also has rules for new registrants claiming credits on some property already on hand when they register (same page).
- Customers. If you mostly bill GST-registered contractors, they claim back the GST you charge, so it usually doesn't cost them anything.
The downside: once registered you must charge GST, file returns and remit on time. Small suppliers who register voluntarily take on all a registrant's obligations. (Memorandum 2-2) If you mostly work for homeowners who can't claim it back, 5% more on every invoice is a real cost to them.
How to register
- Get a business number (BN) if you don't have one. CRA's Business Registration Online sets up a BN and a GST/HST account together. (CRA, RC4022)
- Your GST account number is your 9-digit BN followed by
RT0001. - Put that number on your invoices. CRA lists it among what a supplier's invoice must show for a customer to claim credits on sales of $100 or more. (CRA, Input tax credits)
How often you file, and the Quick Method
When you register, CRA generally assigns an annual reporting period if your taxable sales are $1.5 million or less. You can choose to file quarterly or monthly instead. (CRA, RC4022, Reporting periods; checked November 14, 2026)
Annual filers with net GST of $3,000 or more this year and last year generally have to pay quarterly instalments. For a December 31 year-end those instalments are due April 30, July 31, October 31 and January 31. A self-employed person with a December 31 year-end files the annual GST return by June 15 and pays any remaining GST by April 30. (CRA, When to pay GST/HST instalments; CRA, filing and payment deadlines; checked November 14, 2026)
Most service businesses in Saskatchewan and Alberta can elect the Quick Method instead of tracking GST on every expense. You still charge 5% GST on your invoices, but you remit 3.6% of GST-included sales (1.8% if goods you bought for resale are at least 40% of your GST-included sales), and you get a 1% credit on the first $30,000 of those GST-included sales. You can only use it if your worldwide taxable sales, including GST, are $400,000 or less. You must have been in business for the past 365 days, except if you're a new registrant. Bookkeepers, accountants, lawyers and tax or financial consultants can't use it. Annual filers have to elect by the first day of their second fiscal quarter. You still claim GST separately on equipment and other capital assets you buy. (CRA, RC4058, Quick Method of Accounting; checked November 14, 2026)
Using the same numbers as the take-home example — $120,000 billed before GST, so $126,000 GST-included, and $4,875 to remit the regular way after credits on expenses — the Quick Method remittance would be about $4,236 (3.6% × $126,000, less the $300 credit). The difference stays in the business and is taxable income. Whether it helps depends on how much GST you pay on expenses. (Worked from RC4058 remittance rates and the 1% credit, checked November 14, 2026.)
Make the bookkeeping easy
An invoicing app that adds GST and tracks what you owe saves a lot of end-of-quarter scrambling. Wave's Starter plan is free. FreshBooks and QuickBooks Online add bank feeds and GST reports. See our comparison.
To see what GST, CPP and income tax do to your take-home, try the take-home calculator.
Saskatchewan contractors: PST is separate from GST and has no $30,000 threshold for contractors doing real-property work. See Saskatchewan PST for contractors.
Sources (checked November 14, 2026)
General information, not tax advice. Confirm with CRA or an accountant.