GST HST contractor invoicing in Canada comes down to one number and one habit. The number is $30,000 in taxable sales: go over it and you have to register, charge the tax and file returns. The habit is putting the right tax line on every invoice and treating that money as never yours. Get both right and GST/HST is boring admin. Get them wrong and it turns into a bill from the CRA for tax you never collected.
I learned the business on the tools and then ran a property maintenance company in London with a network of subbies. Different country, different tax, same problem. The trades who got hurt were never the ones who didn't understand tax. They were the ones who spent it.
Updated October 2026. This is general guidance from someone who has run a contracting business, not tax advice. Rates and rules change, so confirm anything you rely on with the CRA or your accountant.
Do you have to register for GST/HST as a contractor?
If your taxable sales go over $30,000, yes. Under that, you're what the CRA calls a small supplier, and registration is optional.
The bit people get wrong is how the $30,000 is counted. It isn't your tax year and it isn't your profit. It's your total taxable sales, before expenses, measured two ways:
- In a single calendar quarter. Go over $30,000 in one quarter and you stop being a small supplier straight away. The job that pushed you over is already taxable.
- Over the last four consecutive calendar quarters. If the running total of any four quarters in a row goes over $30,000, you stop being a small supplier shortly after that quarter ends.
Either way, you have 29 days from the day you stopped being a small supplier to register. If you have associated businesses, their sales can count towards your total too. Ask your accountant if that's you.
For most working trades, $30,000 is not a lot. One decent kitchen reno and a few service calls and you're through it. If you're full time, assume you're registering.
Should you register before you hit $30,000?
Often, yes. Voluntary registration means you can claim back the GST/HST you pay on materials, tools, the van and fuel through input tax credits. If you mostly work for businesses, property managers or other contractors, they're registered too and claim back what you charge them, so the tax costs them nothing.
Where it hurts is homeowner work. A homeowner can't claim the tax back, so to them you just got 5% to 15% more expensive than the unregistered guy down the road. That's a real trade-off for small residential trades. But if you're planning to grow past $30,000 anyway, register early and build the habit now rather than at the worst possible moment.
How to register
It's simpler than people expect:
- Get a Business Number from the CRA if you don't already have one. You can do it online through Business Registration Online, or by phone.
- Add a GST/HST program account to that Business Number. Your GST/HST number is your nine-digit BN followed by RT0001.
- Pick your effective date of registration. If you've already gone over the threshold, it's tied to the day you stopped being a small supplier, not the day you got round to it.
- Note your reporting period. Most small contractors start on an annual filing period by default, but you can usually choose quarterly or monthly.
- Set up a separate bank account or savings pot for collected tax before your first invoice goes out.
Quebec is the exception to most of this. Revenu Québec administers GST and QST there, so if you work in Quebec, go to them, not the CRA.
Which rate do you charge?
GST is 5% across Canada. Five provinces combine it with their provincial tax into a single HST: Ontario at 13%, plus New Brunswick, Newfoundland and Labrador, Nova Scotia and Prince Edward Island at higher rates. Pull the current table from the CRA before you set up your invoice templates. Don't copy rates from a blog, including this one.
For construction work on a property, the rate generally follows where the property is, not where your office is. If you're based in Ottawa and you take a job in Gatineau, that's a Quebec supply. Contractors near a provincial border need to get this right on every quote.
And separate from GST/HST, British Columbia, Saskatchewan and Manitoba have their own provincial sales tax, with specific rules for contractors on materials. That's a different system and worth a separate conversation with your accountant.
What goes on a GST/HST invoice
The CRA scales what it expects on an invoice by the size of the sale. Forget the tiers. Put everything on every invoice and you never have to think about it:
- Your business name, or trading name
- Your GST/HST registration number
- Invoice date
- Client's name and address
- A clear description of the work
- Payment terms
- Subtotal before tax
- The GST or HST amount and the rate, as its own line
- Total including tax
Keep the tax on its own line. Don't bury it in a single all-in price. Your commercial clients need to see the tax and your number to claim their input tax credits, and if it's missing, the first you'll hear about it is an invoice bounced back from their accounts team with the payment held up.
Illustrative example
Fictional scenario for illustration. A renovator in Hamilton, Ontario, does a bathroom for a homeowner at $20,000 before tax. The invoice shows $20,000, HST at 13% of $2,600, and a total of $22,600. The tiler they used is registered and invoiced them $6,000 plus $780 HST. On their next return, the renovator reports $2,600 collected and claims $780 as an input tax credit, along with the HST on materials. They send the CRA the difference.
Simple. The danger is the $2,600 sitting in the business account looking like profit.
The tax isn't your money
Here's the part people hate hearing. That 13% you collect belongs to the government from the second the client pays. You're holding it.
The rule I ran my own company on was this: tax collected goes out of the operating account the week it comes in. Not at filing time. That week. If the business only survives because it's spending tax money, you don't have a business. You have a debt with a delay on it.
The contractors who end up in trouble usually go the same way. Annual filing, a strong year, the money gets spent on a new van and a slow winter, then the return comes due and there's nothing there. The CRA charges interest and penalties on late remittances, and it doesn't care that a client paid you late.
Subbies and GST/HST
If you run a crew of subbies, two things matter.
First, check their numbers. Before you claim an input tax credit on a subbie's invoice, confirm their GST/HST number is real with the CRA's GST/HST Registry. If it's fake or cancelled, you can lose the credit, and that's on you.
Second, unregistered subbies don't charge you tax, and that's fine as long as they're genuinely under the threshold. A subbie billing you $50,000 a year with no GST/HST number is their problem, but it's worth a quiet word.
Separately, if construction is your main business, you probably have to report payments to subcontractors each year on T5018 slips under the Contractor Payment Reporting System. That's income tax, not GST/HST, but it pulls from the same records. Keep subbie invoices clean and both jobs get easier.
Where Plan@Job fits
Plan@Job is AI-powered project and operations management for construction and property businesses. In Plan@Job, the Operator is the contractor business: you run the clients, the project and the subbies and in-house operatives. You can split a job into internal stages with scope, dates, status and costs, while the client only sees the agreed scope and price. Your subbie costs and who did the work stay internal.
On the money side, Maya Collins, the AI Finance Coordinator, prepares deposit requests and overdue payment actions for you to approve. She doesn't send anything or move money on her own. You make that call.
Straight answer on Canada: the live launch is in the UK. Canadian contractors can reserve a spot on the Plan@Job Canada contractors page. I won't tell you how the invoicing handles GST/HST and provincial rates until it's built and checked for Canada. When it is, it'll be on that page.
Until then, do the basics yourself. Count your quarters, register when you have to, put the tax on its own line, and get it out of your operating account the week it lands. That's all most contractors need.
FAQ
Do I charge GST/HST before my registration is approved?
Once you're required to register, you're responsible for the tax on sales from your effective date, whether you charged it or not. That's why you register quickly after going over $30,000. If you didn't charge the tax on early invoices, you may end up paying it out of your own pocket, so talk to your accountant straight away.
Does the $30,000 threshold count my profit or my total sales?
Total taxable sales, before any expenses. A $40,000 year where materials and subbies cost you $30,000 still puts you over. Count what you invoiced, not what you kept.
Can I claim GST/HST on materials if I'm not registered?
No. Input tax credits are only available to registrants. That's the main reason trades who buy a lot of materials or work mostly for businesses register voluntarily before they hit the threshold.