Do you even need a number on the invoice?
Only if you're registered for GST/HST. If your business revenue is at or under $30,000 over four consecutive quarters, you're a small supplier, you don't have to charge GST/HST, and there's simply no registration number to add. The full rule is in our guide on whether you charge GST/HST under $30,000. You can send a clean, legitimate invoice without one.
The moment you register, whether because you crossed the threshold or chose to register early, the number goes on every invoice where you charge tax. That's the short answer. The rest of this page is where it goes, what it looks like, and why your client's bookkeeper cares about it more than you'd expect.
Where the number goes and what it looks like
It belongs in the sender block, next to or just under your business name, so it reads as part of who you are rather than buried in the line items. A GST/HST registration number is your nine-digit CRA business number followed by the letters RT and a four-digit account identifier:
123456789 RT 0001
The RT0001 part is your GST/HST program account. A common mistake is printing the bare nine-digit business number on its own. On its own it isn't enough for your client to rely on, because the RT account is the piece that proves you're registered for GST/HST specifically.
Why your client actually needs it
This is the part most freelancers miss. Your GST/HST number isn't a formality, it's the thing that lets your client claim back the tax you charged them. Businesses recover the GST/HST they pay on expenses through input tax credits, and the CRA only allows that claim if the invoice carries certain information. How much information depends on the invoice total, tax included:
| Invoice total (tax included) | What the invoice must show |
|---|---|
| Under $100 | Your business name, the date, and the total amount |
| $100 to $499.99 | The above, plus your GST/HST registration number and either the tax amount or a note that the price includes GST/HST and at what rate |
| $500 or more | The above, plus your client's name, a description of the work, and the terms of sale |
So on any invoice of $100 or more, tax in, your registration number is a required field for your client to claim their credit. Leave it off and their accounts-payable team can hold the invoice until you send a corrected one. Putting the number on every invoice removes a reason for anyone to sit on your payment.
What about Quebec (QST)?
Quebec runs its own sales tax, the QST, administered by Revenu Quebec. If you're registered for QST, you have a separate QST registration number (it ends in TQ0001), and it goes on the invoice alongside your GST/HST number. You keep both, one for the federal tax and one for Quebec's. A Quebec client claiming their input tax refund needs the QST number for the same reason a federal registrant needs your GST/HST one.
The quick checklist
Before you send, confirm the invoice shows:
- Your business name and your GST/HST registration number ending in
RT0001 - The QST number too, if you're registered in Quebec
- The GST/HST amount charged, or a clear "GST/HST included" note with the rate
- The invoice date and total
Set the number once and it should ride on every invoice automatically. In Loot you enter your GST/HST number in your account settings and it prints in the sender block of every invoice and quote PDF, so you never key it in per invoice or forget it on the one that mattered. Once you register, the rate you charge follows your client's province, covered in which GST/HST rate to charge a client in another province.
FAQ
Do I need a GST/HST number to send an invoice? No. If you're a small supplier under the 30,000 dollar threshold and haven't registered, you don't have a number and you don't charge GST/HST. You can still send a complete, professional invoice. The number is only required once you're registered.
Where does the GST/HST number go on an invoice? In the sender block, next to or just below your business name, so it's clearly tied to you as the supplier. It doesn't belong down in the line items.
What does a GST/HST number look like?
It's your nine-digit CRA business number, then RT, then a four-digit account number, like 123456789RT0001. The RT0001 part is the GST/HST program account, and it's the piece that shows you're registered for GST/HST.
Can a client refuse to pay until I add my registration number? They can hold the invoice. On any invoice of 100 dollars or more, tax included, your client needs your registration number to claim their input tax credit, so accounts-payable teams often pause approval until it's there. Sending it upfront avoids the delay.
Do I need a separate number for Quebec?
Yes. If you're registered for QST, Revenu Quebec issues a separate QST number ending in TQ0001. Put it on the invoice alongside your GST/HST number so a Quebec client can claim both their federal and provincial credits.
Sources
- CRA, "Charge and collect the tax: Receipts and invoices"
- CRA, "Input tax credits"
- Revenu Quebec, "Information to Include on Invoices"
This guide is general information to help you understand the rules. For your specific situation, check the CRA and Revenu Quebec pages above or talk to an accountant.