GST/HST Registration for Small Businesses: When You Must Register and How

One of the most common questions new business owners ask is: do I have to register for GST/HST? The short answer is: once you cross $30,000 in revenue, you have no choice. But there is actually a smart argument for registering earlier — even before you hit that threshold.

Here is everything you need to know.

The $30,000 Rule

In Canada, you are considered a small supplier if your total taxable revenue (before expenses) is $30,000 or less over four consecutive calendar quarters. As a small supplier, registration is optional.

Once you exceed $30,000 in a single quarter, or over the previous four consecutive quarters, you are legally required to register for GST/HST within 29 days.

Important: the $30,000 threshold applies to your gross revenue, not your profit. Even if your business is barely breaking even, if you are invoicing over $30,000, you need to register.

GST vs HST: Which One Applies to You?

It depends on the province where your customer is located (not where you are).

GST only (5%): Alberta, BC, Manitoba, Saskatchewan, Quebec (Quebec uses QST separately)
HST (combined): Ontario (13%), New Brunswick (15%), Nova Scotia (14% as of April 1, 2025), PEI (15%), Newfoundland and Labrador (15%)

If you are selling to customers in multiple provinces, you charge the rate applicable to the customer’s province — this is called the place of supply rule.

Why You Might Want to Register Voluntarily

Even if you are under $30,000, voluntary registration can make financial sense if you are spending significant money on business expenses. Here is why: once you are registered, you can claim Input Tax Credits (ITCs) — refunds on the GST/HST you paid on business purchases.

For example: if you are just starting out and spent $20,000 on equipment (paying $2,600 in HST in Ontario), voluntary registration lets you recover that $2,600.

The trade-off is that you must now collect GST/HST from clients and remit it to CRA on time. But for B2B businesses, most clients are also registered and can claim their own ITCs — so the extra charge does not actually cost them anything.

How to Register

Registration is straightforward and free. You can do it:

Online: Through your CRA My Business Account at canada.ca
By phone: Call 1-800-959-5525
Through your accountant: They can register on your behalf using their representative access

You will receive a Business Number (BN) with a GST/HST program account (RT0001). This is a 9-digit number followed by RT0001, which you put on all your invoices.

Filing Periods: Monthly, Quarterly, or Annually?

Once registered, CRA assigns you a filing period based on your revenue:

Annual: If your taxable revenue is under $1.5 million
Quarterly: If your taxable revenue is between $1.5 million and $6 million
Monthly: If your taxable revenue is over $6 million

You can always request more frequent filing if it helps your cash flow. Annual filers with taxes owing over $3,000 may still need to make quarterly instalment payments.

What Happens If You Register Late?

If CRA determines you should have registered earlier and did not, they can back-assess you for all the GST/HST you should have collected, plus interest and penalties. This can be a significant surprise bill.

If you realize you crossed the $30,000 threshold but missed the 29-day window, register immediately and disclose proactively — CRA’s Voluntary Disclosure Program can reduce or eliminate penalties in some cases.

Special Cases

Taxi, ride-share, and delivery drivers: Must register for GST/HST from day one, regardless of revenue.
Non-resident sellers: If you are a non-Canadian selling digital services to Canadian consumers, the Digital Services Tax rules may require you to register for a simplified GST/HST account.
Zero-rated and exempt supplies: Some goods and services are zero-rated (you charge 0% GST/HST but can still claim ITCs) or exempt (you cannot charge or claim). Basic groceries, most medical services, and residential rent are examples of exempt supplies.

Quick Checklist

Track your gross revenue every quarter
Register within 29 days of crossing $30,000
Consider voluntary registration if your startup costs are high
Charge the correct GST/HST rate based on your customer’s province
Keep all receipts so you can claim Input Tax Credits
File and remit on time to avoid penalties

Not sure if you need to register now, or whether voluntary registration makes sense for your situation? Book a consultation with us — we will review your revenue and help you set up GST/HST properly from the start.