Goods and Services Tax Number: Format, Registration, and Filing

A GST number in Canada is the 15-character identifier the Canada Revenue Agency issues to a business so it can legally collect and remit the 5% federal Goods and Services Tax (and, where it applies, the Harmonized Sales Tax). Most businesses making taxable sales in Canada need one once their revenue passes $30,000 over four consecutive calendar quarters. The number is tied to the business’s broader CRA account and acts as proof to customers and suppliers that the business is a registered participant in the tax system.

What a GST Number Looks Like

Every GST/HST number follows the same format: a nine-digit Business Number, then the two-letter program code “RT,” then a four-digit reference number. A typical number reads 123456789 RT0001. The first nine digits identify the business across all CRA programs. The “RT” flags the GST/HST account specifically. The four-digit suffix lets a business separate multiple GST/HST accounts if it has more than one. When you verify a supplier through CRA’s online registry, you enter only the first nine digits.¹

Who Has to Register

Section 240 of the Excise Tax Act requires any person making taxable supplies in Canada through a commercial activity to register for GST/HST, unless they qualify as a small supplier, only sell real property outside a business, or are a non-resident not carrying on business in Canada.²

The small supplier threshold is $30,000. You qualify as a small supplier if the total value of your worldwide taxable supplies over the previous four calendar quarters stayed at or below that amount, including sales by any associated entities. Public service bodies get a higher threshold of $50,000.³ If you cross $30,000 during a single calendar quarter, you lose small supplier status immediately before the sale that pushes you over.⁴

Taxi operators and commercial ride-share drivers are the major exception. Section 240(1.1) of the Excise Tax Act requires every small supplier who carries on a taxi business to register regardless of revenue.² That requirement has extended to self-employed ride-share drivers since July 1, 2017.⁵

When Voluntary Registration Makes Sense

Businesses earning less than $30,000 can still register. The main reason to do so is access to Input Tax Credits, which let you recover the GST/HST you pay on business expenses like supplies, equipment, and rent. Without registration, that tax stays a cost. Voluntary registration also removes friction if most of your customers are other registered businesses that need proper tax invoices.

The trade-off matters. Once you register, you must charge GST/HST on your taxable sales, file returns on schedule, and keep records that meet CRA standards. If your customers are mostly consumers who cannot claim ITCs themselves, adding tax to your prices could make you less competitive against unregistered competitors selling below the threshold. CRA generally requires voluntarily registered businesses to stay registered for at least one year before they can request cancellation.

How to Apply for a GST Number

Registration uses Form RC1, which also serves as the application for a Business Number if you don’t already have one.⁶

The fastest route is CRA’s online portal, My Business Account. After logging in, you go to the registration section, enter your information, and confirm it with a digital signature. Online applications typically process within minutes to a couple of business days.

Paper applications by mail are still accepted. Send the completed Form RC1 to your designated tax centre. Mailed applications often take several weeks. CRA’s confirmation letter includes your GST/HST number, the effective date of your registration, and your assigned filing period.

One change worth noting: as of November 3, 2025, CRA no longer accepts Business Number or program account registrations by phone.⁷ Older guides that mention calling in to register are out of date.

Information You Need Before You Apply

Have the following ready:

Legal business name, exactly as it appears on your incorporation or registration documents.
Social Insurance Number, for sole proprietors and partners, so CRA can link the business to your personal tax records.
Your existing Business Number, if you already have one from other CRA programs like payroll or corporate tax.
A description of your business activity, which CRA uses to classify your account.
Projected annual revenue, which determines your initial filing frequency.
Director information for corporations, including names and identification numbers.
Banking details (branch number, institution code, and account number) for direct deposit of refunds.
A physical business address for official correspondence.

Names must match your incorporation documents exactly. Even small discrepancies can trigger a rejection and slow things down.

What You Have to Do After You Register

Once you have a number, three obligations kick in: charge and remit tax on taxable sales, issue invoices that meet the CRA rules, and file returns on the schedule CRA assigns.

Invoice Requirements

The Input Tax Credit Information (GST/HST) Regulations set out what invoices must include, and the requirements scale with the sale amount because your customers need this paperwork to claim their own ITCs:⁸

Under $100: supplier’s name, invoice date, and total amount paid. Your GST/HST number is not required at this level.
$100 to $499.99: the above, plus your GST/HST registration number and either the tax charged or a statement that the total includes GST/HST.
$500 and above: the above, plus the buyer’s name, a description of the goods or services, and the terms of payment.

An incomplete invoice blocks your customer from claiming an ITC on that purchase.⁹

Filing and Reporting

CRA assigns your reporting period based on your annual revenue: monthly, quarterly, or annual. You can request a more frequent period if you prefer faster refund cycles, but you cannot file less frequently than your assigned default.¹⁰ On each return you report GST/HST collected, subtract the ITCs you’re claiming, and either remit the difference or request a refund.

Claiming Input Tax Credits

ITCs are the financial upside of registration. To claim one, you must have been registered during the reporting period, the expense must have been for commercial activities, GST/HST must have been paid or payable, and you must have documentation before filing.⁹ Keep receipts organized; CRA can ask for them during an audit, and a missing receipt means a denied credit.

Verifying a Supplier’s Number

Before claiming an ITC on a large purchase, confirm the supplier’s registration. CRA’s free online GST/HST Registry lets you search by the first nine digits of the supplier’s account number, the business name, and the transaction date.¹ If the registration doesn’t check out, you cannot claim an ITC on that purchase and should not pay GST/HST to that supplier. Save the search results with your records.

What Happens If You Don’t Register When You Should

Operating above the small supplier threshold without registering doesn’t cancel the tax you owe. You still owe the GST/HST you should have collected, and Section 280 of the Excise Tax Act adds interest at the prescribed rate on any amount not remitted by the deadline, running from the day after it was due until the day it’s paid.¹¹

Separately, CRA can demand a return from any person it believes should have filed one. Failing to comply carries a flat $250 penalty under Section 283. The bigger financial hit usually comes from accumulated interest and the retroactive tax liability itself, which can stretch back years if CRA concludes you should have been registered long ago.

If Your Business Is Based Outside Canada

A business based outside Canada that carries on business within Canada must register for GST/HST unless it qualifies as a small supplier under the same $30,000 threshold.¹² Whether a non-resident is “carrying on business in Canada” depends on factors like where agents or employees are located, where inventory is held, where contracts are executed, and where services are performed.¹³

Non-residents who register receive a Business Number and can claim ITCs to recover GST paid on goods imported into Canada for commercial use. CRA may require a security deposit to cover potential GST/HST liability and will notify the registrant in writing of the amount and terms.¹² A separate simplified registration regime has applied to non-resident digital service providers selling to Canadian consumers since July 1, 2021.¹³

1
Canada Revenue Agency. Confirming a GST/HST Account Number
2
Department of Justice Canada. Excise Tax Act – Section 240
3
Department of Justice Canada. Excise Tax Act – Section 148
4
Canada Revenue Agency. GST/HST Memorandum 2.2 – Small Suppliers
5
Canada Revenue Agency. GST/HST and Commercial Ride-sharing Services
6
Canada Revenue Agency. RC1 Request for a Business Number and Certain Program Accounts
7
Canada Revenue Agency. Register for a GST/HST Account
8
Department of Justice Canada. Input Tax Credit Information (GST/HST) Regulations
9
Canada Revenue Agency. Input Tax Credits
10
Canada Revenue Agency. Reporting Requirements and Deadlines
11
Department of Justice Canada. Excise Tax Act – Section 280
12
Canada Revenue Agency. Doing Business in Canada – GST/HST Information for Non-Residents
13
Canada Revenue Agency. GST/HST and E-commerce