The $30,000 HST threshold every Ontario STR host misses

You don't register for HST when you "feel ready" — you're legally required to once your rolling 12-month STR revenue crosses $30K. Here's how the math actually works.

Most Ontario STR hosts know HST exists. Far fewer know that the $30,000 small-supplier threshold is a rolling 12-month window, not a calendar-year one — and that crossing it triggers a hard 29-day registration deadline. Miss the deadline and the CRA can assess HST on every booking back to the day you crossed, even though you never collected it.

What counts toward the $30,000

Room revenue from all your STR properties combined (not per property).
Cleaning fees you charge guests.
Pet fees, extra-guest fees, early check-in fees.
Direct-booking revenue AND Airbnb/Vrbo revenue.

What does NOT count: MAT you collected and remitted, refundable damage deposits, refunds you issued.

How the rolling window works

On the last day of every calendar quarter, add up the last 4 quarters of qualifying revenue. If the sum is over $30,000 at any point — even if no single quarter was big — you have crossed.

Example: $9K Q1, $11K Q2, $7K Q3, $4K Q4 = $31K. You crossed on December 31, even though you never had a "big" quarter.

The 29-day rule

Once you cross, you have until the end of the month AFTER the month you crossed to register for HST. Cross on December 31, you must register by January 31. CRA''s My Business Account is the fastest path — registration is same-day.

What changes after registration

You collect 13% HST on every taxable booking (Ontario rate). Airbnb collects and remits HST on your behalf for short-term stays since July 2022 — but you still need to remit on direct bookings yourself.
You can claim Input Tax Credits (ITCs) on HST you paid for: cleaning supplies, professional fees, repairs, furnishings, advertising, utility bills (pro-rated to the rental use).
You file an HST return: annually if revenue is under $1.5M (most hosts), quarterly above that.

The most expensive mistake

Hosting through the summer, crossing $30K in August, and not realizing until you file taxes in March. By then the CRA can:

Backdate your registration to the day you crossed.
Assess 13% HST on every booking since then — money you never collected from guests.
Add interest and a failure-to-register penalty.

A $40,000 revenue year can become a $5,000 surprise bill.

What to do

Track rolling 4-quarter revenue every quarter, not just at year-end.
If you''re anywhere over $25K rolling, voluntarily register early. You can always file nil returns; you can''t un-do a missed deadline.
Keep every receipt with HST on it from day one. ITCs are the only thing that makes registration neutral instead of a tax hit.