A GST/HST number lets a business charge GST or HST on its sales and claim back the tax it pays on its own purchases as input tax credits. Most businesses must register once their sales pass $30,000. Smaller ones can choose to. The registration itself is free and, for most Canadian businesses, done online in one sitting.
Who has to register
You must register if you make taxable sales, leases or other supplies in Canada and you are not a small supplier. For most businesses, you stay a small supplier as long as your taxable supplies do not exceed $30,000, tested two ways:
- In a single calendar quarter: if one quarter goes over $30,000, you stop being a small supplier with the sale that crosses the line, and you charge GST/HST on that sale.
- Over four consecutive calendar quarters: if the total of the last four quarters goes over $30,000 without any one quarter doing it, you stop being a small supplier at the end of the month after that quarter.
The total counts your worldwide taxable supplies, zero-rated ones included, and those of your associates. It leaves out financial services, sales of capital property and goodwill. Once you are no longer a small supplier, the CRA gives you 29 days from your effective date of registration to register.
Some businesses must register whatever their sales: self-employed taxi operators and commercial ride-sharing drivers register from the day they start giving rides. Charities, public institutions and other public service bodies use different thresholds ($50,000 in taxable supplies, and a $250,000 gross revenue test for charities and public institutions).
Registering before you have to
A small supplier that makes taxable supplies can register voluntarily. You then charge GST/HST on your sales, and you can claim input tax credits on what you buy for the business. The effective date is usually the day you ask, or up to 30 days before.
How to register with the CRA
The CRA's Business Registration Online (BRO) service is the route for most resident businesses, and since November 3, 2025, new business numbers and program accounts can no longer be registered by phone. If you call, you are sent to BRO.
- Sign in to your CRA account (you need one to use BRO).
- Choose Business account on the welcome page and select Register a business.
- Enter your details: your name, Social Insurance Number, date of birth and home postal code, then the business name, type, owners and their SINs, physical and mailing addresses, a description of the main activity and, for a new business, an estimate of annual revenue. You also pick the effective date of registration and your fiscal year.
- Save or print the confirmation. Your business number and account details appear on screen and are not sent to you separately.
If you cannot register online, you can mail Form RC1, Request for a Business Number and Certain Program Accounts, to your tax centre. A few cases still go by phone or paper: reactivating a closed program account, a Canadian business owned only by non-residents, and a business owned by another business. If your temporary SIN starts with 9, you must use BRO.
In Quebec: register with Revenu Québec
If your business is physically located in Quebec, the GST/HST is administered by Revenu Québec, and you register for the GST and the QST together with them. The small supplier test is the same $30,000. Use the Register a New Business service if you have no file with Revenu Québec yet, the registration service in My Account for businesses if you already do, or form LM-1-V, Application for Registration.
Some Quebec businesses must register for the QST even as small suppliers, for example retail sellers of tobacco or fuel, sellers of alcoholic beverages, and sellers or lessors of new tires.
What your GST/HST number looks like
Your business number (BN) is nine digits. Each CRA program account adds two letters and four digits to it: RT is GST/HST. The first GST/HST account of business number 123456789 reads 123456789 RT0001. That full number goes on your invoices and receipts. A QST number from Revenu Québec has its own format: ten digits, then TQ and four digits.
Your customers need it. To claim an input tax credit on a purchase of $100 or more, a registered buyer must have the supplier's GST/HST registration number on the invoice or receipt, and many will check it on the CRA's GST/HST Registry.
After you register
You charge GST/HST on taxable sales from your effective date, file returns for each reporting period, and claim input tax credits for the tax on your business purchases. Every one of those credits needs a receipt or invoice behind it that shows the supplier and the tax. Smartbills keeps that file for you: the Smartbills app reads each tax line on a paper receipt separately, GST and QST or HST, along with the registration numbers printed on it, email receipt capture collects the invoices that arrive by email, and vendor management keeps each supplier's tax number on its record. When it is time to sign in and file your GST/HST return, the paperwork is already in one place.