If you are starting a business in Ontario, sooner or later you will run into the GST/HST number question. Maybe a client asked for it before they would pay an invoice. Maybe your accountant mentioned it. Maybe you just read that you are supposed to have one and now you are not sure if that is true for you.
Here is the plain version of how to get a GST/HST number in Ontario: how it works, who actually needs one, and how to register without overcomplicating it.
What a GST/HST number actually is
GST is the federal Goods and Services Tax. HST is the Harmonized Sales Tax, which is what Ontario uses because the province combined its sales tax with the federal GST into a single 13% rate. When people say "GST/HST number," they are talking about the same thing: an account with the Canada Revenue Agency that lets you collect this tax from your customers and send it to the government.
The number itself is tied to your CRA business number. It usually looks like your nine-digit business number followed by "RT0001."
Do you even need one?
This is the part most people get wrong, so it is worth slowing down.
You are required to register once your business earns more than $30,000 in revenue over four consecutive calendar quarters. The CRA calls this the small supplier threshold. Stay under it and registration is optional. Cross it and you have 29 days to register from the day you go over.
- The $30,000 is based on total worldwide revenue from taxable sales, not your profit.
- It is measured on a rolling basis, not per calendar year. Four quarters in a row.
- Some businesses register voluntarily even while small, because being registered lets them claim back the GST/HST they pay on their own expenses (these are called input tax credits). For a business with real startup costs, that can be worth more than the hassle of filing.
If you are a taxi or ride-share driver, the threshold does not apply to you. You have to register from your first dollar.
How to register for a GST/HST number
There are three ways to register, and they are not equally painless.
- Online through CRA My Business Account. This is the standard route. You will need your business number first. If you do not have one yet, the registration process can create one for you at the same time.
- By phone. You can call the CRA business line and register over the phone if you would rather talk to a person.
- By mail or fax using Form RC1. This is the slow option and there is rarely a good reason to choose it.
When you register, the CRA will ask for your business start date, your estimated annual revenue, your reporting period, and your fiscal year-end. Most small businesses are assigned an annual reporting period by default, which means you file once a year. You can ask for quarterly or monthly if it suits your cash flow better.
What happens after you register
Once you have the number, three things change. You start charging 13% HST on your taxable sales in Ontario. You put your GST/HST number on your invoices, because clients who are themselves registered will want it to claim their own credits. And you file a return on whatever schedule you were assigned, reporting what you collected and subtracting what you paid out.
Getting it set up at the right time
Registration itself is administrative and you can do it yourself. The decisions around it are where it gets less obvious: whether to register voluntarily, how the timing lines up with incorporating, and how the tax flows once you have employees or sell across provinces. Those are worth a short conversation with a qualified accountant before you commit.
If you are incorporating in Ontario, Korporex sets up your CRA business number and GST/HST registration as part of the online filing, so your tax accounts are in place from day one.