Updated Checked by the Tax-Services.ca editorial team How we check
A GST lookup in Canada means checking a supplier’s GST/HST account number in the CRA’s GST/HST Registry, a free online tool. You enter the first nine digits of the number, the business name and the date of the sale, and the registry tells you whether that business was registered on that date.
How to do a GST lookup in Canada
Have the invoice or receipt in front of you. You need three things, and the registry is strict about the format.
| What to enter | How to enter it |
|---|---|
| GST/HST account number | First nine digits only, no letters |
| Business name | Legal, operating or trading name, as on the invoice |
| Transaction date | The date on the invoice or receipt |
Invoices often print the number with letters and more digits after the first nine. Leave all of that out. A full number looks like 123456789 RT 0001, and only the 123456789 part goes in the box. If the supplier hasn’t put a number on the invoice, ask for it. You can also call the CRA business enquiries line at 1-800-959-5525 when you can’t find it.
The CRA’s own page on confirming a GST/HST account number sets out the same steps, and it explains the point of the exercise: to help make sure your input tax credit claims only include tax charged by someone who is registered.
Why bother checking a supplier’s number?
If your business claims input tax credits, the GST/HST you claim must have been charged by someone who was registered. The CRA built the registry for that reason. A fake number on an invoice can put your claim at risk, and you’d find out only after a review.
Is it worth doing for every invoice? No. Check new suppliers, large invoices and anything that looks odd, like a number with the wrong number of digits or a business that only sends text messages. For your regular electricity provider, skip it.
Say Marcus, who runs a small landscaping firm in Barrie, gets a $4,000 invoice from a contractor he has never used. The invoice shows $520 of HST. That’s $520 he plans to claim back. A thirty-second lookup before he pays is cheap insurance next to losing that credit later.
What if the registry says the number isn’t valid?
First, check your typing. A transposed digit is the most common reason. Then check the name against the invoice and the date against the day of the sale, since the tool matches all three. If it still comes back empty, go back to the supplier and ask them to confirm the number in writing.
If they can’t, think hard about paying the HST at all. You can’t claim a credit for tax charged by someone who wasn’t registered when they charged it, and a business that adds a tax line without a valid number is a red flag in its own right.
What the registry can’t tell you
The registry confirms registration. It doesn’t say whether the business is honest, whether it charged the right amount, or whether it filed its returns. The date matters too, because a business can be registered today and not have been on the day of your purchase. That’s why the tool asks for the transaction date.
Quebec adds a wrinkle. The CRA page says QST can’t be checked there, so for the Quebec part you contact Revenu Québec directly. And if you’re an individual shopper with no business, you rarely need any of this. You pay the tax shown on the receipt, and what you can do is work it out yourself with the GST and HST calculator to see whether the total looks right.
Checking the tax on an invoice
A quick sum catches most errors. Take an Ontario invoice of $1,000 before tax. HST at 13% is $130 and the total should be $1,130. In Alberta the same invoice carries $50 of GST and totals $1,050. In Saskatchewan it’s $50 GST plus $60 PST, for $1,110.
If the invoice only shows the final total, the reverse HST calculator backs the tax out. In the three provinces with a separate provincial tax, use the GST and PST calculator instead. Quebec has its own GST and QST calculator.
When a business has to register at all
Lookups come up because some businesses don’t have a number. The small supplier threshold is $30,000 of taxable sales, measured over four consecutive calendar quarters or in any single quarter, and a business under it doesn’t have to register or charge GST/HST. That’s the usual reason a small seller, a freelancer or a hobby business has no number on the invoice. Once a business goes over, the CRA’s general information guide for GST/HST registrants says it must register within 29 days of the sale that took it over the line.
If a supplier does charge GST/HST but can’t give you a number, be careful and ask. A small supplier who hasn’t registered has no right to add the tax to your bill. Some sectors have their own rules, so check the details for your own situation on canada.ca before you register or decide not to.
The sources behind this page
The lookup steps and the nine digit rule come from the Canada Revenue Agency‘s page on confirming a GST/HST account number. The example rates use the 2026 federal and provincial rates in our data, which come from CRA and provincial pages. This site has no link with the CRA and can’t look numbers up for you, so use the registry itself.
Frequently asked questions
Is the GST/HST Registry free?
Yes. The CRA service is free to use.
Do I enter the RT0001 part of the number?
No. Enter only the first nine digits and no letters.
Can I look up a QST number there?
No. The CRA page says QST checks go through Revenu Québec.
What if the supplier gave me no number?
Ask for it. If you still can't find it, the CRA business enquiries line at 1-800-959-5525 can help.
Does a valid number prove the invoice is right?
No. It only confirms registration on the date you entered. Check the tax amount yourself.
- GST, HST, PST and QST explained for every province
Which GST, HST, PST or QST applies where you shop or sell in Canada, the 2026 rates for every province, who must register and how to add or remove tax