GST Number in Canada: What It Is and How to Look One Up

Short answer: A GST number is the GST/HST account number the Canada Revenue Agency (CRA) gives a business when it registers. It has 15 characters: your nine-digit business number (BN), the letters RT, and a four-digit reference, usually 0001, as in 123456789 RT0001. Once you are registered, it must appear on invoices and receipts for taxable sales of $100 or more. To check a supplier’s number, enter the first nine digits, their business name and the transaction date in the CRA’s GST/HST Registry.

These are the rules in force in 2026. They are set by the CRA, and in Quebec, Revenu Québec runs GST/HST for businesses located there. This guide is for sole proprietors, freelancers and contractors who either have a GST/HST number to print on their own invoices or pay suppliers who charge them tax. If you don’t have a number yet, start with how to register for GST/HST. If you need the rest of the invoice too, see how to invoice in Canada as a freelancer, or browse the Canada guides hub.

What is a GST number in Canada?

A GST number is your business number with a GST/HST program account attached to it. The CRA builds every program account number the same way: a unique nine-digit BN, a two-letter program identifier and a four-digit reference number.

Part	Example	What it identifies
Business number (BN)	123456789	Your business, across every CRA account you hold
Program identifier	RT	The GST/HST program
Reference number	0001	Which GST/HST account this is (the first one is 0001)
Full GST/HST account number	123456789 RT0001	What goes on your invoices

“GST number”, “HST number”, “GST/HST number” and “GST/HST registration number” all mean the same thing. There is one federal account for both taxes, and a business in Ontario or Nova Scotia gets the same kind of RT number as one in Alberta. The only difference is the rate it charges. One exception: since July 1, 2023, businesses on the simplified GST/HST regime, mostly non-resident digital sellers, have RT9999 numbers, so the two kinds of registration are easy to tell apart.

Do I need a GST number as a sole proprietor?

Only once you register for GST/HST. An unincorporated sole proprietor needs a BN only when they open a CRA program account, such as GST/HST, payroll or import-export. If you trade under your own name and stay a small supplier, you report your income on your personal return and don’t need either number.

You must register once your worldwide taxable revenue is more than $30,000 in a single calendar quarter or over the last four consecutive calendar quarters. Taxi and commercial ride-sharing drivers must register from their first fare, whatever their revenue. You can also register voluntarily below $30,000. If you’re unsure which applies, the registration guide goes through the test with worked numbers.

Where do I find my own GST/HST number?

Look on the confirmation from when you registered. If you registered online through Business Registration Online, the CRA tells you to save or print your BN and GST/HST account number during that session. The number also appears on CRA letters about the account and in My Business Account, where you manage it.

If you can’t find it, call the CRA’s Business Enquiries line at 1-800-959-5525. If your business is physically located in Quebec, your GST/HST account is with Revenu Québec, so call them at 1-800-567-4692 instead. Once you have the number, put the whole thing into whatever you invoice with. Don’t use just the nine-digit BN.

Where does the GST number go on an invoice?

On every invoice, receipt or contract for a taxable sale of $100 or more, once you are registered. The rule exists because of your customer: a registered business can recover the GST/HST it pays through an input tax credit (ITC), and the CRA only accepts the claim if the paperwork meets its documentary requirements. The requirements increase with the size of the sale.

Total sale amount	What the invoice or receipt must show
Under $100	Supplier’s business or trading name, the date, the total paid or payable
$100 to $499.99	All of the above, plus the supplier’s GST/HST registration number and an indication of the total GST/HST charged
$500 or more	All of the above, plus the buyer’s name, a brief description of the goods or services, and the terms of payment

Here is how that looks on a $1,200 job for an Ontario client, invoiced by an Ontario sole proprietor:

Invoice 2026-031                              Date: 2026-10-06
From: Priya Shah Bookkeeping, Hamilton ON
GST/HST No.: 123456789 RT0001
Bill to: Northline Fabrication Ltd., Burlington ON

Monthly bookkeeping, September 2026          $1,200.00
HST (13%)                                      $156.00
Total due                                    $1,356.00
Terms: Net 15

Two common mistakes: printing only the nine-digit BN, and printing a provincial number in its place. A Quebec QST number or a British Columbia PST number is a separate registration that a provincial authority issues, and it doesn’t support a GST/HST credit. If you work in Quebec, the QST side is covered in Quebec sales tax for contractors. To work out the tax line itself, see how to calculate GST/HST.

How do I look up a GST number in the GST/HST Registry?

Use the CRA’s GST/HST Registry. You need three things from the supplier’s invoice:

1. The GST/HST account number. Enter only the first nine digits, which is the BN part.
2. The business name. Use the supplier’s legal, operating or trading name as it appears on the invoice or the sign at their place of business.
3. The transaction date. This is the date on the receipt, invoice, contract or other document.

The Registry then tells you whether that business was registered for GST/HST on that date. You can’t use it to find a number from a name, because every search starts from the number. If a supplier won’t give you their number, call Business Enquiries at 1-800-959-5525 and ask the CRA to confirm whether they are registered.

What if a GST number doesn’t show up as registered?

Check what you typed before you assume anything. According to the Registry FAQ, most mismatches come from the business name, the order of the words in the name, the number or the date. If you get “Not registered on the transaction date entered”, check all three and search again. If a search by the name on the invoice still returns nothing, ask the supplier what exact name they gave the CRA.

The reason to bother is the money. Say you’re a contractor in Calgary and you buy $2,400 of materials from a new supplier, plus $120 GST at 5%. If you’re registered, that $120 comes back to you as an ITC on your next GST/HST return, but only if the supplier’s number is valid. If the number doesn’t verify, sort it out with the supplier before you claim. Often the cause turns out to be a name or date typed differently, but don’t assume that. The return itself is covered in how to file a GST/HST return.

Is a GST number the same as a business number?

No. The BN is the nine-digit core that identifies your business, and the GST/HST number is that BN with RT0001 added. The CRA’s list of program accounts you may need shows that other accounts, such as payroll, hang off the same BN with their own two-letter identifiers. Your BN stays the same whichever accounts you open. Each account just adds its own suffix. So when a client asks for your “business number” for GST purposes, give them the full GST/HST account number, BN plus RT0001, because that is what their input tax credit claim needs.

What records back up your GST/HST numbers, and where does Keel fit?

Both sides of the GST/HST system run on paperwork. The tax you charge comes from your invoices, and the tax you claim back comes from supplier invoices and receipts that show a valid number. Keeping both organized is the part you control.

Keel: Invoice Maker & Receipts, by Ilura Technology OÜ, is an iPhone app for people who work for themselves. It makes estimates that become invoices in one tap, PDF invoices, and records of receipts, expenses and business mileage, each kept under the job it belongs to. Records stay on your iPhone: there is no account, no bank connection and no cloud sync, and the App Store privacy label reads “Data Not Collected.”

To be clear about the limits: Keel doesn’t check numbers against the GST/HST Registry, doesn’t connect to the CRA, doesn’t work out the tax you owe and doesn’t file GST/HST returns. Its job is to keep the invoices and receipts those steps rely on. Keel is free to use with no invoice limit, and free invoices carry a small “Made with Keel” footer. Keel Lifetime is a one-time purchase ($249.99 USD; the App Store shows your local price) that adds custom branding, a signature, premium templates and accountant-ready exports. Keel: Invoice Maker & Receipts on the App Store.

Frequently asked questions

Can I look up a GST number by business name? No. The CRA’s GST/HST Registry confirms a number you already have. It doesn’t search by name. You enter the first nine digits of the number, the business name and the transaction date, and it tells you whether that business was registered on that date. If you don’t have the number, ask the supplier, or call Business Enquiries at 1-800-959-5525.

Is an HST number different from a GST number? No. GST and HST share one federal account, so a business in an HST province such as Ontario gets the same kind of number as a business in a GST-only province such as Alberta: the nine-digit BN plus RT0001. People call it an HST number in HST provinces, but it is the same GST/HST account number, and the same Registry checks it.

Do I have to put my GST number on invoices under $100? It is only required from $100 up. Below $100, the CRA’s documentary requirements ask for the supplier’s name, the date and the total, not the registration number. You can still print the full number on every invoice. It costs nothing, saves a client asking for it, and means you never have to think about which invoices cross the line.

Does a sole proprietor need a business number? Only when they open a CRA program account. An unincorporated sole proprietor who isn’t registered for GST/HST, doesn’t run a payroll and doesn’t import or export can report self-employment income without a BN. You get your BN automatically when you register for GST/HST, whether that is because you passed $30,000 or because you chose to register voluntarily.

What should I do if a supplier’s GST number comes back as not registered? First check the business name, the order of words in the name, the number and the transaction date, then search again. If it still fails, ask the supplier for the exact name they registered with the CRA, or call Business Enquiries to confirm their status. Hold off claiming an input tax credit for that tax until the number checks out, because a claim without a valid number doesn’t meet the CRA’s documentary requirements.

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This article is general information, not tax advice. Consult a qualified accountant or tax professional.