When Do You Have to Register for GST? The Small Supplier Rules Every Alberta Business Owner Needs to Know

Running a small business in Alberta — whether you're a Leduc contractor, a rural farmer, or a self-employed professional anywhere in the province — comes with a lot of moving parts. One of the questions that comes up early — and gets answered incorrectly surprisingly often — is whether you're required to register for GST. The short answer is: it depends on your sales. The long answer involves a few specific rules under the Excise Tax Act (ETA) that are worth understanding in detail, because the consequences of missing your registration deadline are no small matter.

The Starting Point: Small Suppliers Don't Have to Register

Under ETA 240(1)(a), a person who qualifies as a "small supplier" is not required to register to collect and remit GST. This is the provision that gives smaller businesses a break — you don't need to navigate the GST system until your business reaches a certain scale.

The operative question, then, is: what makes you a small supplier? And more importantly: when do you stop being one?

The $30,000 Threshold — And the Rolling 4-Quarter Rule

ETA 148(1) defines when a person ceases to be a small supplier: when the total value of your taxable supplies exceeds $30,000 over any four consecutive calendar quarters.

That sentence has a detail in it that trips up a lot of business owners — and, frankly, a lot of bookkeepers too.

The four quarters are rolling. They do not reset on January 1.

For clarity, the four calendar quarters are:

• Q1: January 1 – March 31
• Q2: April 1 – June 30
• Q3: July 1 – September 30
• Q4: October 1 – December 31

This is one of the most common mistakes in practice: assuming that the clock starts fresh at the beginning of each calendar year. It does not. The CRA looks at any four consecutive calendar quarters — which means the relevant window shifts forward one quarter at a time, every quarter, all year long. Your Q2 through Q1 total matters just as much as your Q1 through Q4 total. If your cumulative taxable sales in any rolling four-quarter window exceed $30,000, you have crossed the threshold regardless of where the calendar year begins or ends.

What Counts Toward the $30,000?

Here's another detail that surprises many business owners: zero-rated supplies are included in this calculation.

Zero-rated supplies are goods and services that are taxable under the ETA but at a rate of 0% — meaning GST applies in law, even though the effective charge to the customer is zero. Many agricultural products fall into this category.

Example: If you are a canola farmer and you sell $30,000 worth of canola, those sales count toward your $30,000 threshold even though canola is zero-rated and your customers paid no GST at the point of sale. Once you cross that threshold, you are required to register — full stop.

This catches many producers and agricultural operators off guard. The absence of a GST charge on your invoices does not mean your sales are invisible to this calculation.

What Is Excluded from the Calculation

Not everything your business receives counts. The following are excluded from the small supplier threshold calculation:

• Sales of goodwill — proceeds from the sale of the goodwill of a business
• Sales of capital property — property that is capital in nature (e.g. equipment, real property used in your business)
• Financial services — exempt supplies such as interest income, dividends, and similar financial transactions

These exclusions exist because they represent atypical or one-time transactions rather than the ongoing commercial activity the threshold is designed to capture. A business that sells a piece of equipment for $40,000 has not necessarily become a commercial operation at scale — so that sale doesn't push them over the line.

What Happens Once You Cross the Threshold?

Once your taxable sales exceed $30,000 in a rolling four-quarter period, two things happen in sequence.

First, your obligation to collect GST begins. Under ETA 148(1), you are required to start collecting GST on your taxable supplies beginning on the first day after the end of the calendar month immediately following the quarter in which you exceeded the threshold. In plain English: if you crossed $30,000 during Q2 (April through June), your obligation to collect GST kicks in on August 1 — the day after July ends.

Second, you must register. Under ETA 240(2.1), once that collection obligation begins, you have 29 days from that date to apply for GST registration with the CRA. Using the same example: your collection obligation starts August 1, which means your registration deadline is August 30.

Missing this deadline doesn't make the obligation go away — it just means you've been collecting (or should have been collecting) GST without being registered, which creates real exposure on a CRA audit.

The Associates Rule: You Can't Split Your Way Around the Threshold

The $30,000 threshold is not calculated on a per-entity basis in isolation. Under ETA 148(1), it applies to you and your associates on a combined basis.

Associates under the ETA generally includes related individuals, corporations under common control, and partnerships with overlapping ownership — essentially, parties that are not truly dealing with each other at arm's length.

This rule exists specifically to prevent the most obvious workaround: stopping at $25,000, incorporating a new business, and running another $25,000 through the new entity. That doesn't work. The CRA will look at the combined sales of you and your associated persons, and both entities will be counted together toward the threshold.

There's a related scenario that's equally important: if you already operate a GST-registered business and you incorporate a new company that makes taxable supplies, that new company must collect GST from the moment it opens its doors — because your combined sales as an associate group already exceed the threshold. The new company does not get its own fresh $30,000 room. The existing registration of your associated business means the small supplier exemption is already exhausted, and the obligation to collect begins on day one.

What If You Exceed $30,000 in a Single Quarter?

Everything above deals with ETA 148(1) — exceeding $30,000 over a rolling four-quarter window. But ETA 148(2) addresses a separate and more immediate situation: what happens when you exceed $30,000 within a single calendar quarter.

If your taxable sales in a single quarter push past $30,000 — say, a large contract closes in October and you invoice $35,000 in Q4 — the rules tighten considerably. Under ETA 148(2), you cease to be a small supplier at the moment the supply that causes you to exceed the threshold is made. There is no quarter-end grace period. Your obligation to collect GST begins on that specific transaction.

Practically, this means the supply that crosses the $30,000 line is itself taxable, and every supply after it in that quarter is taxable as well. The obligation doesn't wait until next month — it kicks in mid-quarter, on the day you cross the line.

Example: You are a consultant who has been operating as a small supplier. By November 15, you have invoiced $28,000 in Q4 (October 1 – December 31). On November 20, you issue an invoice for $5,000, bringing your Q4 total to $33,000. That November 20 invoice is the one that crosses the threshold — which means GST applies to it. You are now required to collect GST on that invoice and on every invoice you issue for the remainder of Q4. You then have 29 days from November 20 to register with the CRA. Any invoices issued between November 20 and your registration date that did not include GST create a liability you will need to address.

The same 29-day registration window under ETA 240(2.1) applies from that point.

You Don't Have to Wait: Voluntary Registration Under ETA 240(3)

So far we've covered when you're required to register. But ETA 240(3) also permits a small supplier to register voluntarily — even if your sales are well below $30,000 and you have no legal obligation to do so.

Why would you want to? One word: ITCs.

As we've covered in a previous guide, Input Tax Credits allow you to recover the GST you paid on business expenses. If you are not registered for GST, you cannot claim ITCs — those amounts simply become part of your cost of doing business. For a business that is growing, investing in equipment, or carrying meaningful operating expenses, the GST paid on inputs can add up quickly.

Voluntary registration flips that equation. Once registered, every dollar of GST you pay on qualifying business expenses becomes recoverable. Depending on your expense profile, voluntary registration can result in a meaningful refund from the CRA each filing period — even when your revenue is below the mandatory threshold.

If you're a small supplier who is spending money to grow your business, it's worth having a conversation with your accountant about whether voluntary registration makes sense before you hit $30,000.

Quick Reference: The Small Supplier Registration Rules

The Bottom Line

The small supplier rules are one of the areas of Canadian tax law where a small misunderstanding can have a real financial impact. Whether it's assuming the four-quarter window resets in January, overlooking zero-rated sales, or missing how the associates rules apply to a newly incorporated business — the gaps between what most people assume and what the ETA actually says are costly ones.

If your sales are approaching $30,000, or you've recently started a second business, now is the time to review your position — not after the CRA does it for you.

This article is for general informational purposes only and does not constitute legal or tax advice. For guidance specific to your situation, consult a CPA or Canadian tax professional.