Once you're registered for GST, one of the first practical questions is: how often do I actually have to file? The answer isn't the same for every business. The CRA uses your sales volume to determine your required filing frequency — and as your business grows, that frequency can change. Getting it right matters, because filing on the wrong schedule can result in late-filing penalties and interest.
This article walks through the rules from the ground up.
Step One: Calculating Your “Threshold Amount”
Before you can determine your filing frequency, you need to know your threshold amount — the CRA's measure of your annualized taxable sales. This is defined under ETA 249(1), and it uses the following formula:
- A = the total value of your taxable supplies in the base year, excluding sales of goodwill, financial services, capital property, and goods exported under Schedule VI, Part V of the ETA
- B = the number of days in your base year (your fiscal year)
The formula exists to level the playing field for businesses with fiscal years shorter or longer than 365 days — it converts your actual sales into an annualized equivalent so comparisons are consistent.
What Counts as a Taxable Supply Here?
Just like with the small supplier threshold we covered in a previous article: zero-rated supplies are included. If you are a grain farmer selling canola, wheat, or other zero-rated agricultural products, those sales count toward your threshold amount even though your customers paid no GST at the point of sale. The rate of tax is zero — but the supply is still taxable in law, and it counts.
The Associates Rule Applies Here Too
Your threshold amount is not calculated in isolation. Under ETA 249(1), the threshold amount includes the combined taxable supplies of you and all of your associates. The same logic from the small supplier rules applies: you cannot split your sales across related entities to land in a more favourable filing category. The CRA adds it all together.
Example: You own two businesses. One generates $900,000 in taxable sales and the other generates $800,000. On their own, each business would fall under $1.5 million. But your combined threshold amount is $1,700,000 — which puts both businesses in the quarterly or monthly filing category.
Step Two: The Quarterly Threshold
In addition to the annual threshold amount, ETA 249(2) introduces a concept called the quarterly threshold — which is the total of your taxable supplies for all of the fiscal quarters completed so far within the current fiscal year.
Unlike the rolling four-quarter window used for the small supplier rules, the quarterly threshold resets at the beginning of each new fiscal year. You start fresh every year. This is the one place in the GST rules where the calendar (or fiscal) year actually does matter.
The quarterly threshold is what the CRA uses to determine mid-year filing frequency changes, which we'll walk through below.
Filing Frequency at a Glance
Before getting into the details of each category, here's a summary of your options based on your threshold amount:
| Threshold Amount | Annual Filing | Quarterly Filing | Monthly Filing |
|---|---|---|---|
| $1,500,000 or less | ✅ Available | ✅ Available | ✅ Available |
| Above $1,500,000 up to $6,000,000 | ❌ Not available | ✅ Available | ✅ Available |
| Above $6,000,000 | ❌ Not available | ❌ Not available | ✅ Required |
In short: smaller businesses have the most flexibility, larger businesses have less, and very large businesses have none — they must file monthly.
Annual Filing — ETA 248(1)
Under ETA 248(1), you are eligible to file your GST return annually if your threshold amount is $1,500,000 or less. Annual filing is the least administratively demanding option — one return per year — and is well-suited to businesses with stable, modest revenue and straightforward GST affairs.
When Does Annual Filing End?
Under ETA 248(2) and 248(3), you can continue filing annually until one of two things happens:
- You elect to switch to quarterly or monthly filing (your choice, at any time), or
- Your threshold amount exceeds $1,500,000, at which point you are required to move to quarterly or monthly filing.
The timing of when you exceed $1,500,000 during the year determines when the switch takes effect:
- You exceed $1,500,000 during Q1 (January 1 – March 31): You must begin filing quarterly starting in Q2 (April 1).
- You exceed $1,500,000 during Q2 (April 1 – June 30): You must begin filing quarterly starting in Q3 (July 1).
- You exceed $1,500,000 during Q3 (July 1 – September 30) or Q4 (October 1 – December 31): You don't need to switch mid-year. You begin filing quarterly at the start of the next fiscal year.
Example: Your business has been growing steadily and you've been filing annually. By May 15, your year-to-date taxable sales hit $1,600,000 — crossing the threshold in Q2. You don't need to do anything for Q2 itself, but starting July 1 (the beginning of Q3), you are now required to file quarterly. Your annual return covers up to that transition point; from Q3 onward, you file a separate return each quarter.
Quarterly Filing — ETA 247(1)
Under ETA 247(1), you are eligible to file quarterly if your threshold amount is $6,000,000 or less. Quarterly filing means four GST returns per year — one for each of Q1, Q2, Q3, and Q4 — with each return due one month after the end of the quarter.
Quarterly filing strikes a balance between the simplicity of annual filing and the cash flow precision of monthly filing. For many growing businesses, it's the most practical option.
When Does Quarterly Filing End?
Under ETA 247(2), you can continue filing quarterly until one of three things happens:
- You elect to file monthly — you can switch to monthly at any time.
- Your threshold amount drops below $1,500,000 and you elect to switch to annual filing — if your business slows down, you can move back to annual, but you must make that election (it doesn't happen automatically).
- Your threshold amount exceeds $6,000,000 — if your sales grow past $6 million during a quarter, you are required to switch to monthly filing. The switch takes effect at the start of the first fiscal quarter immediately following the quarter in which you exceeded $6,000,000. Unlike the transition from annual to quarterly filing, this switch happens mid-year — you do not get to wait until the next fiscal year.
Example: Your business has been filing quarterly. During Q2 (April 1 – June 30), your combined sales cross $6,500,000. You must begin filing monthly starting July 1 — the first day of Q3, immediately following the quarter in which you crossed the threshold. Waiting until the next fiscal year is not an option, and filing quarterly after that point could expose you to penalties.
Monthly Filing
If your threshold amount exceeds $6,000,000, monthly filing is mandatory. There are no exceptions and no elections available — twelve returns per year, due at the end of the month following each reporting period.
Businesses at this scale typically have dedicated accounting staff or external bookkeepers who handle GST compliance as a matter of course, so the administrative burden is generally manageable in context.
Switching Filing Frequencies — The Election Rules Under ETA 250(d)(ii)
If you want to proactively switch your filing frequency — rather than being bumped by a threshold change — there are deadlines you need to be aware of.
The rules under ETA 250(d)(ii) set out how much time you have to file your election after the start of a new fiscal year:
- Switching from quarterly to annual filing: You have 3 months from the start of your fiscal year to file the election with the CRA.
- Any other switch (annual to quarterly, annual to monthly, quarterly to monthly, or monthly to quarterly): You have 2 months from the start of your fiscal year to file the election.
These are hard deadlines. If you miss the window, you're locked into your current filing frequency for that fiscal year and will need to wait until the next year to make the change.
Example: Your fiscal year runs January 1 to December 31. You've been filing quarterly and your sales have dropped — you'd like to switch to annual filing to reduce your administrative workload. You have until March 31 (3 months after January 1) to file that election with the CRA. Miss that date, and you'll be filing quarterly for the rest of the year.
Example: You've been filing annually and your business is growing. You'd prefer the discipline of quarterly reporting. Your fiscal year starts January 1, so you have until February 28 (2 months after January 1) to file your election to switch to quarterly.
Quick Reference: GST Filing Frequency Rules
| Rule | Provision | Detail |
|---|---|---|
| Threshold amount formula | ETA 249(1) | (A × 365) ÷ B; includes associates; zero-rated sales count |
| Quarterly threshold | ETA 249(2) | Cumulative sales for completed quarters in the current fiscal year; resets each fiscal year |
| Annual filing eligibility | ETA 248(1) | Threshold amount ≤ $1,500,000 |
| Exit from annual filing | ETA 248(2) & 248(3) | Elect to change, or exceed $1,500,000 mid-year |
| Quarterly filing eligibility | ETA 247(1) | Threshold amount ≤ $6,000,000 |
| Exit from quarterly filing | ETA 247(2) | Elect to change, drop below $1.5M and elect annual, or exceed $6,000,000 |
| Election deadline: quarterly → annual | ETA 250(d)(ii) | 3 months after start of fiscal year |
| Election deadline: all other switches | ETA 250(d)(ii) | 2 months after start of fiscal year |
The Bottom Line
Your GST filing frequency isn't something you set once and forget. As your business grows, your required filing frequency can change — sometimes mid-year, and sometimes with very little notice. Understanding the thresholds, knowing when a switch is triggered, and being aware of the election deadlines can save you from unexpected compliance gaps.
If your sales are approaching $1.5 million or $6 million, or if you'd simply like to change your current filing schedule, talk to your accountant before the fiscal year starts — that's when your options are widest and your deadlines are furthest away.
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.