HST Number Explained (Canada)

An HST tax number is the Canada Revenue Agency (CRA) account number a business uses to collect, report and remit the Harmonized Sales Tax. It is not a separate registration from the federal GST account: in the provinces that use HST, the federal and provincial portions are blended into one tax, and the CRA issues a single GST/HST account under your Business Number. That account number — your Business Number plus an RT reference — is what most people mean when they say HST number or GST/HST number.

What an HST number actually is

The CRA gives each business one nine-digit Business Number (BN) and then adds separate program accounts for the taxes and programs that business uses. A GST/HST account is typically written as your BN followed by RT and a four-digit reference number, most often 0001 — for example, 123456789RT0001. The same BN can also carry a payroll account (RP) or a corporate income tax account (RC) if those apply to you.

For a sole proprietor, the BN belongs to the business, not to your personal SIN, even though the CRA generally asks for your SIN when you first register. Because it is one account, there is no separate 'GST number' and 'HST number' issued to the same business in an HST province. What changes between provinces is the tax you charge, not the account you hold.

HST number vs GST number vs Business Number

These terms get used interchangeably, but they describe different things.

For a closer comparison of the BN and the tax account, see Business Number versus GST/HST number.

Do you need an HST number in Canada?

You generally must register for a GST/HST account once your taxable revenue exceeds the small supplier threshold. That threshold is set by the CRA and can change, so confirm the current amount on canada.ca before you decide. Some businesses must register regardless of revenue: the CRA has long required taxi and commercial ride-sharing operators to register from their first dollar of revenue. Registration is also voluntary for many smaller businesses, which can make sense if you want to claim input tax credits on business purchases.

• You sell taxable goods or services in Canada.
• Your revenue is above the small supplier threshold, or you register voluntarily.
• You charge GST/HST on invoices and file GST/HST returns, even in periods with no sales.

The full rule set is covered in the GST/HST registration threshold in Canada and in how to register for GST/HST in Canada.

How to register for an HST tax number

1. If you do not already have a BN, apply for one — you can request the BN and the GST/HST account at the same time. See how to get a Business Number in Canada.
2. Register through CRA My Business Account or the CRA's online business registration service, which is the fastest route for most sole proprietors.
3. Register by phone or by mail if you prefer; the CRA will confirm your account number and your assigned reporting period.
4. Businesses based in Quebec register for GST and QST through Revenu Québec rather than the CRA, so the steps differ.

Once you are set up, logging in through CRA My Business Account is how you file returns, update details and view notices.

Where to find your HST number and how it is used

Your HST number appears on the confirmation the CRA sends after registration, inside CRA My Business Account, and on returns and notices you have filed. After registering, you charge GST/HST on taxable supplies, show your account number on invoices where required, and file returns for your assigned reporting period. You can generally claim input tax credits for GST/HST paid on business purchases, which offsets the tax you remit.

If you are self-employed, the amounts you collect and remit flow through your T2125 filing as part of your business income and expenses. Records supporting your returns should generally be kept for six years, and your reporting frequency can change as your revenue grows.

Common mistakes to avoid

• Quoting your SIN instead of your BN and RT account number on invoices.
• Assuming the GST/HST account appears automatically when you register a business name — provincial name registration and CRA tax accounts are separate.
• Ignoring the account after a slow year; a registered business usually still has to file, even with no revenue.
• Leaving the account open after you stop selling — see how to cancel a GST/HST account in Canada.
• Changing address, ownership or business name without telling the CRA.

Confirm your specific obligations with the CRA or a qualified tax professional. This page is general information as of the current tax year, not tax advice.