An Ontario HST number is a federal GST/HST program account registered with the Canada Revenue Agency (CRA). Eligible applicants use Business Registration Online (BRO) through a CRA account. The HST account is distinct from an Ontario business-name or incorporation registration.
What does the number look like?
A GST/HST account combines a nine-digit federal business number, RT and a four-digit reference, for example 123456789 RT0001. The BN identifies the entity; RT identifies the GST/HST program account. If you already have a BN for another CRA program, use it when adding the GST/HST account.
Do you need to register?
Most businesses use the $30,000 small-supplier tests, counting worldwide taxable supplies, including zero-rated supplies and applicable supplies of associates, before expenses. Taxi and commercial rideshare operators must register regardless of the threshold. Public service bodies can have different tests. See CRA’s threshold guidance.
- One quarter: If supplies exceed $30,000 in one calendar quarter, charge tax on the supply that crosses the limit. The effective date must be no later than that supply; apply within 29 days of the effective date.
- Four quarters: If four consecutive quarters exceed the limit without a one-quarter excess, small-supplier status ends at the end of the following month. The effective date is no later than the first supply after that point; charge from that date and apply within 29 days of it.
A qualifying small supplier can register voluntarily. That may permit eligible ITCs, but also requires collecting tax on taxable supplies, keeping records and filing returns.
How to obtain the account
- Gather your legal and operating names, structure, owner or director details, address, fiscal year-end, main activity and estimated taxable sales. Have an existing BN ready if the entity has one.
- Sign in to a CRA account and select the business registration option. Request the GST/HST program account, enter the applicable effective date and review the information.
- Submit the application and save or print the BN and GST/HST account details from the session.
Some applicants cannot use BRO; the CRA lists the appropriate alternatives. A sole proprietor with a temporary SIN beginning with 9 must use BRO, whereas directors, partners and trustees with that type of SIN use Form RC1. Non-residents should follow the CRA’s non-resident instructions. Phone is no longer a general new-account registration route.
Ontario example: crossing the threshold
Assume a consultant has no other relevant taxable supplies or associated-business sales in the test periods. They bill $15,000, then $12,000, then $5,000 in one calendar quarter. The third sale raises the total to $32,000. If the $5,000 sale is an ordinary taxable supply made in Ontario, charge 13% HST, or $650, on the whole sale. The registration effective date is no later than that sale; apply within 29 days.
After registration
For ordinary taxable supplies made in Ontario, HST is generally 13%; the treatment can differ for other supplies or places of supply. File the returns assigned to your account. You may claim ITCs for eligible tax on purchases used in commercial activities, subject to documentation and other conditions; not every buyer can automatically recover HST.
Related guides
Sources
Official guidance checked October 17, 2026.