The four-quarter test
Add up your taxable sales for the last four calendar quarters (Jan–Mar, Apr–Jun, Jul–Sep, Oct–Dec). If the total is over $30,000, you're no longer a small supplier. You have to start charging GST/HST from your first sale after the end of the month that follows that quarter, and register within 29 days.
The one-quarter trap
If you go over $30,000 in a single calendar quarter — one big kitchen or basement job can do it — you stop being a small supplier on that very sale. You have to charge HST on the job that pushed you over, and register within 29 days. For a contractor this is the common surprise: price the big job with HST from the start.
Can I register before I reach $30,000?
Yes — the CRA lets you register voluntarily. Some contractors do it because it lets them claim back the HST they pay on materials and tools (input tax credits). The trade-off: you then charge HST to every client. Ask your bookkeeper which is better for you.
What changes on my invoices
Once you're registered, each invoice shows your business number with the RT account, the HST as its own line, and the total. Our HST calculator and invoice generator lay it out for you.
How to register
Online through the CRA's Business Registration Online, by phone, or by mail. Step by step: How to get an HST number in Ontario.
Need the invoice too?
Put the amount into our free HST invoice generator — your business, your client, the work, PDF in two minutes.
Running a crew? CrewHub turns clock-ins into payroll hours and quotes into invoices with HST. 14 days free, no card.