The short answer
A business number (BN) is the CRA's 9-digit ID for your business. A sole proprietor only needs one when they open a CRA program account, usually GST/HST (RT0001). You get it online, instantly, through Business Registration Online.
GST/HST registration is mandatory once your taxable sales pass $30,000 in one calendar quarter or over the last four consecutive calendar quarters. Rules as of September 2026.
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What a business number is
The BN is a 9-digit number the Canada Revenue Agency uses to identify a business in all its dealings with the federal government. On its own it doesn't do much. What matters are the program accounts hung off it: each one adds a two-letter identifier and a 4-digit reference number, so a GST/HST account looks like 123456789 RT0001.
According to the CRA's page on when you need a BN (checked September 2026), an unincorporated business only needs a BN "when you register for program accounts." A corporation always gets one.
The program accounts a small service business might need
| Code | Account | You need it when |
|---|---|---|
| RT | GST/HST | You charge GST/HST: mandatory past $30,000 in taxable sales, optional below it. |
| RP | Payroll deductions | You hire an employee and deduct CPP, EI and income tax from their pay. |
| RC | Corporation income tax | You incorporate. Sole proprietors don't get one; you file a T2125 with your personal return. |
| RZ | Information returns | You file slips such as T5018 (construction subcontractors) or T5. |
| RM | Import-export | You import or export goods commercially. |
From the CRA's program accounts you may need, as of September 2026. Most one-person businesses only ever open RT.
A BN isn't a provincial business registration either. Registering a business name with your province (Ontario, BC or Alberta) is a separate step, though some provinces pass the details to the CRA and a BN arrives by email.
How to get a business number
Since November 3, 2025, new BNs and program accounts have to be registered online, according to the CRA's announcement. The exceptions (reactivating a closed account, businesses with only non-resident owners, businesses owned by another business) still use the phone or Form RC1.
- Sign in to your CRA account (the same one you use for your personal taxes).
- Choose Add account, then Business Account, then Business Registration Online.
- Enter your details: legal name, SIN, business name if you use one, address, what the business does, and when it started.
- Pick the program accounts you need. For most people that's GST/HST only. You'll be asked your expected sales and your reporting period (annual is the default for small businesses).
- Save the confirmation. The BN and account numbers appear when you finish, and the CRA doesn't mail them to you.
BRO is available 21 hours a day, 7 days a week. The CRA's pages list no registration fee.
The $30,000 small supplier test, precisely
Most people search "do I need a GST number" because of this rule. You're a small supplier, and registration is optional, until your revenue from worldwide taxable supplies passes $30,000. The CRA's page on when to register and start charging GST/HST gives two ways to pass it, as of September 2026:
| You pass $30,000 | You stop being a small supplier | You start charging |
|---|---|---|
| In a single calendar quarter | Immediately | On the sale that took you over $30,000 |
| Over four consecutive calendar quarters (but not in one) | At the end of the month after the quarter you went over | On your first sale after that |
Either way, you have 29 days from your effective date of registration to register. Calendar quarters are January to March, April to June, July to September and October to December.
Two details that trip people up:
- It's revenue, not profit. Count what clients paid before expenses. Zero-rated sales count; exempt supplies, sales of capital property and financial services don't.
- It's a rolling window, not your tax year. Earning $28,000 last calendar year doesn't settle it. Every quarter, add up the last four.
A worked example: a dog walker bills $7,000, $8,000, $7,500 and $8,200 over four quarters. Total: $30,700. She stops being a small supplier at the end of the month after the fourth quarter, starts charging GST/HST on her next sale, and has 29 days to register. The GST/HST guide walks through tracking the threshold, the rates by province and what to do when you're close.
Should you register voluntarily?
Below $30,000 you can still register. It's a real choice, not a technicality:
Reasons to register early
- You claim input tax credits on business purchases: equipment, supplies, a vehicle's business share.
- Your clients are mostly businesses, who can claim the GST/HST back themselves.
- You expect to pass $30,000 soon and want to set prices once.
- Some commercial clients prefer registered suppliers.
Reasons to wait
- Your clients are households, so 5% to 15% on top is a real price increase for them.
- You'll file GST/HST returns even in slow years.
- You have to stay registered for at least one year before you can cancel.
- A service business with few expenses has little to claim back.
The one-year minimum comes from the CRA's Guide RC4022, checked September 2026.
What changes on your invoices after you register
Once you're registered, your invoices carry the tax and the information your clients need to claim it back. For any sale of $100 or more, the CRA's input tax credit rules expect:
- your GST/HST number (123456789 RT0001), and
- the GST/HST charged, shown as an amount or rate, or a statement that the price includes it.
At $500 or more, add the client's name, a brief description of the service and your payment terms. How to write an invoice has the full tier-by-tier list and an annotated example.
You also charge the right rate for where the client is: 5% GST in Alberta, BC, Saskatchewan, Manitoba, Quebec and the territories (plus provincial sales tax where it applies), 13% HST in Ontario, and 14% or 15% HST in the Atlantic provinces. The GST/HST guide has the full table.
The quick method, briefly
Filing GST/HST doesn't have to mean tracking tax on every receipt. With the quick method, you charge the normal rate but remit a smaller fixed percentage of your sales (including the tax), and generally don't claim input tax credits except on capital purchases. You're eligible if your annual worldwide taxable sales are $400,000 or less.
For a service business selling in its own province, the remittance rates in the CRA's Guide RC4058 (checked September 2026) are 3.6% in GST-only provinces, 8.8% in Ontario, 9.4% in Nova Scotia and 10.2% in the 15% HST provinces, with a 1% credit on the first $30,000 of eligible sales each year. For a low-expense service business, that often leaves more in your pocket than the regular method. You elect it with the CRA; an accountant can tell you whether it suits you.
Where this shows up at tax time
Your BN goes on your Form T2125. If you're registered, you report sales including GST/HST and then subtract the tax, so it isn't counted as income. With the quick method, the difference between what you collected and what you remitted is added back as income. The self-employed tax calculator estimates what you'll owe on the profit.
Common questions
What is a business number in Canada?
A business number (BN) is the 9-digit number the Canada Revenue Agency uses to identify a business. When you add a CRA program account, such as GST/HST or payroll, the account number is the BN plus a two-letter program identifier and a 4-digit reference number, for example 123456789 RT0001 for GST/HST.
How do I get a business number?
Online, through Business Registration Online (BRO): sign in to your CRA account, add a business account and choose Business Registration Online. Since November 3, 2025, new BNs and program accounts must be registered online, with a few exceptions such as businesses with only non-resident owners. You get the BN immediately. In some provinces, registering a business name with the province also gets you a BN.
Do I need a business number as a sole proprietor?
Only when you need a CRA program account, most often GST/HST. A sole proprietor under the $30,000 small supplier threshold, with no employees, can run their business on their SIN and report the income on Form T2125, with no BN at all.
When do I need to register for GST/HST?
When your taxable sales pass $30,000 in a single calendar quarter, or over the last four consecutive calendar quarters. Pass it in one quarter and you charge GST/HST starting with the sale that took you over. Pass it over four quarters and you stop being a small supplier at the end of the following month. Either way, you have 29 days from your effective date to register.
Do I need a GST number if I make less than $30,000?
No. Below $30,000 you're a small supplier and registration is optional. You can register voluntarily, which lets you claim input tax credits on business purchases, but then you have to charge GST/HST to your clients and stay registered for at least one year.
Is a business number the same as a GST/HST number?
Not quite. The BN is the 9-digit root. Your GST/HST number is the BN plus RT0001. That full number is what goes on your invoices, and clients need it to claim input tax credits on purchases of $100 or more.
Does it cost anything to get a business number?
The CRA's registration pages list no fee for a business number or a GST/HST account. Websites that charge to "get your business number" are private filing services, not the CRA.
Does Biller put my GST/HST number on invoices?
Biller invoices can carry GST/HST, so once you're registered you can add the tax and your number to your invoices. Biller doesn't track your position against the $30,000 threshold for you; the GST/HST guide shows how to check it yourself.