When do I have to register for HST?

There are two tests and either one ends your small supplier status. The first adds up your taxable supplies over the four calendar quarters before the current one. The second looks at a single calendar quarter on its own, and it is the one that catches contractors.

What happens if I go over $30,000 in one quarter?

You stop being a small supplier at the moment of the supply that takes you over. That supply is itself taxable, so the HST on it is owed whether or not you charged it, and there is no grace month.

Is the four-quarter test a rolling twelve months?

No. Calendar quarters are fixed to January, April, July and October. What counts is the four calendar quarters immediately before the one you are in. A rolling twelve months is a different period, and so is your fiscal year.

How long do I have to register once I cross the threshold?

Twenty-nine days from the day you made the supply that took you over the threshold.

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Ontario, Canada

Do you have to charge HST yet?

There are two tests, not one. Everyone writes about the four-quarter one. The one that catches a contractor is the single-quarter one, and it has no grace month.

What you billed, by calendar quarter

Taxable revenue, before tax. Include zero-rated work and anything billed by an associated business. Leave out the sale of capital property such as a truck.

Jul to Sep 2025

Oct to Dec 2025

Jan to Mar 2026

Apr to Jun 2026

Jul to Sep 2026 so far

Filled in with an example so the page answers before you type anything. Change any field and the answer, and the link to it, become yours.

Your four preceding quarters

$30,500

Against a threshold of $30,000.

You are past the four-quarter test

Your four preceding calendar quarters add up to more than the threshold, so you are past the four-quarter test. Small supplier status runs out at the end of the month after the quarter you crossed in.

Small supplier status runs out on Jul 31, 2026, and registration follows within 29 days, by Aug 29, 2026.

Excise Tax Act s.148(1)

What was tested

Jul to Sep 2025
under the threshold on its own
$7,000
Oct to Dec 2025
under the threshold on its own
$9,000
Jan to Mar 2026
under the threshold on its own
$6,500
Apr to Jun 2026
under the threshold on its own
$8,000
Jul to Sep 2026 (the quarter you are in)
under the threshold on its own
$5,000
The four preceding calendar quarters added up
tested against $30,000, the four-quarter test
$30,500

The four-quarter test

Add your taxable supplies over the four, or fewer, calendar quarters before the one you are in. Cross the threshold there and you stop being a small supplier at the end of the month following that quarter, which is the grace month everybody has heard of.

Excise Tax Act s.148(1)

The single-quarter test

Cross the threshold inside one calendar quarter and you stop being a small supplier at that moment. The supply that takes you over is itself taxable, and there is no grace month at all. One good job does it.

Excise Tax Act s.148(2)

Questions this page answers

When do I have to register for HST?: There are two tests and either one ends your small supplier status. The first adds up your taxable supplies over the four calendar quarters before the current one. The second looks at a single calendar quarter on its own, and it is the one that catches contractors.
What happens if I go over $30,000 in one quarter?: You stop being a small supplier at the moment of the supply that takes you over. That supply is itself taxable, so the HST on it is owed whether or not you charged it, and there is no grace month.
Is the four-quarter test a rolling twelve months?: No. Calendar quarters are fixed to January, April, July and October. What counts is the four calendar quarters immediately before the one you are in. A rolling twelve months is a different period, and so is your fiscal year.
How long do I have to register once I cross the threshold?: Twenty-nine days from the day you made the supply that took you over the threshold.

Or watch the threshold without doing this again

Invoice through the platform and both tests run against your real revenue as it lands, so the quarter that takes you over the line tells you on the invoice that does it, not at the end of the year.

Then HST goes on the invoice at the right rate, holdback comes off the pre-tax value, and the tax you have set aside sits in your books in plain words instead of a spreadsheet column.

Open the demo business Read the HST guide

Where these figures come from

hst_small_supplier_threshold (CA-ON) Published source Last read from the source Aug 12, 2026.
hst_registration_window_days (CA-ON) Published source Last read from the source Aug 12, 2026.

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