- The Business Number (BN) is a nine-digit identifier the Canada Revenue Agency assigns to a business the first time it registers for any federal program account.
- The HST number is not a separate, standalone identifier — it is a program account layered on top of your existing Business Number.
- You will only ever have one BN for a given legal entity.
If you just registered a new business in Ontario, you have probably run into two different-looking numbers on your CRA paperwork and wondered whether they are the same thing. They are not. Your Business Number and your HST number — more precisely, your GST/HST account — serve related but distinct purposes, and mixing them up can cause real problems, from invoices that look wrong to a registration application filed under the wrong identifier.
Understanding how these two numbers relate to each other is one of the first pieces of tax literacy every Ontario business owner needs, whether you operate as a sole proprietor, a partnership, or a newly incorporated company. This article breaks down what each number identifies, how CRA links them together, and when you actually need to apply for the second one.
Your CRA Business Number: The Foundation
The Business Number (BN) is a nine-digit identifier the Canada Revenue Agency assigns to a business the first time it registers for any federal program account. Think of it as your business's account number with the CRA — the same way a Social Insurance Number identifies you personally, the BN identifies your business as an entity CRA tracks.
You typically receive a BN when you incorporate federally or provincially, or the first time you register for a CRA program such as payroll, corporate income tax, or GST/HST. Once assigned, the same nine digits stay with your business for as long as it exists, across every CRA program it ever registers for.
The HST/GST Account: A Program Attached to Your BN
The HST number is not a separate, standalone identifier — it is a program account layered on top of your existing Business Number. When you register for GST/HST, CRA adds a two-letter program identifier ("RT" for GST/HST) and a four-digit reference number to your BN. The result reads as your nine-digit BN followed by "RT0001."
This structure matters because a single business can hold several program accounts under one BN at the same time: an RT account for GST/HST, an RP account for payroll, an RC account for corporate income tax, and so on. They all share the same root nine digits but represent separate registrations for separate obligations.
How the Numbers Fit Together
| Identifier | What it identifies | Typical format |
|---|---|---|
| Business Number (BN) | Your business as a single entity in CRA's system | 9 digits |
| GST/HST account | Your registration to charge, collect, and remit HST | BN + "RT" + 4-digit reference |
| Payroll account | Your registration to remit source deductions for employees | BN + "RP" + 4-digit reference |
| Corporate income tax account | Your corporation's income tax filing account | BN + "RC" + 4-digit reference |
You will only ever have one BN for a given legal entity. You can add multiple program accounts to it over time as your business takes on new obligations.
When You Need Each One
You typically receive a BN as soon as you register for any CRA program — most businesses get one automatically the moment they incorporate or first register with CRA. You need an HST/GST account specifically once your business is required to register, which generally turns on how much revenue it brings in. The exact revenue threshold changes from time to time, so confirm the current figure with CRA or a tax professional rather than relying on a number you've seen elsewhere. Many businesses below that line also register voluntarily, often to recover HST paid on their own purchases through input tax credits.
Until you are registered for GST/HST, you should not be charging HST on your invoices or quoting an HST number to clients — doing so before registration creates its own compliance problem.
Common Mistakes New Business Owners Make
- Assuming the BN alone lets you charge HST. It does not — you need the separate RT account.
- Quoting the wrong number on an invoice. Clients and vendors expect your full RT account number, not just your bare nine-digit BN.
- Registering for HST before it's needed, without a plan. Voluntary registration can make sense, but it also means you must start charging, collecting, and remitting HST going forward — get advice first.
- Forgetting that closing a business means closing every program account. Winding down a corporation does not automatically deregister its HST account; that has to be done separately.
Frequently asked questions
Do I need a new Business Number every time I register for a new CRA program?
No. Your BN stays the same for the life of your business. Each new CRA program — GST/HST, payroll, corporate tax — adds a new program account onto that existing BN rather than issuing you a fresh number.
I incorporated but haven't registered for HST yet — is that normal?
Yes, this is common. Incorporating gives you a BN, but registering for GST/HST is a separate step you take once you need or want to charge HST. Many new corporations operate for a period before their HST registration becomes necessary.
Can two different businesses share one HST number?
Generally no. Each legal entity — each corporation, or each individual operating as a sole proprietor — registers under its own BN and its own GST/HST account, though specific rules apply to related corporations and to one person's multiple business activities.
What happens if I use my BN as though it were my HST number on an invoice?
Clients may reject the invoice, since the bare BN doesn't confirm you're registered to charge HST. Once you're registered, always quote the full program account number, not just the nine-digit root.
This is a tax question
Start a file online — flat, published fees, reviewed by a licensed Ontario lawyer before a dollar is owed.