Canadian · Validation
GST/HST number format checker.
Check that a GST/HST account number has the structure the CRA describes: a 9-digit business number, the program identifier RT and a 4-digit reference number. Format only; it does not tell you whether the account is registered.
Short answer: a GST/HST number looks like 123456789 RT 0001: nine digits, the letters RT, and four more digits. The CRA publishes no check digit for the business number, so only the structure can be tested here.
Inputs
Result
Enter a number and press Check.
How a GST/HST account number is built
The CRA says a program account number consists of a 9-digit business number (BN) that is unique to the business, a 2-letter program identifier that shows the account type, and a 4-digit reference number that tells apart accounts of the same type. Its example, 123456789 RT 0001, is a GST/HST account under business number 123456789.
| Code | Account type |
|---|---|
| RT | GST/HST |
| RP | Payroll deductions |
| RC | Corporation income tax |
| RZ | Information returns |
| RR | Registered charities |
| RG | Air Travellers Security Charge |
| RD | Excise duty |
| RE | Excise tax and special levies |
| RM | Import and export |
| RN | Insurance premium tax |
| LT | Luxury Tax |
| RU | Underused Housing Tax |
| PT | Global minimum tax |
This tool accepts only RT as a GST/HST account. If you enter another CRA program identifier, it tells you which account type it is rather than calling it valid.
Why the BN digits are not checked
The CRA does not publish a check-digit rule for the business number, so there is nothing to recompute. For the BN alone, see the Business Number validator.
Format check, not a GST/HST Registry search
To confirm that a supplier is registered, use the CRA's GST/HST Registry. The CRA says to enter the first nine digits of the account number there.
Sources
Retrieved October 2026. Rules can change; check the issuing authority if a result matters.
FAQ
What format is a GST/HST number?
A 9-digit business number, the program identifier RT and a 4-digit reference number, for example 123456789 RT 0001 (CRA).
What does RT mean in a GST/HST number?
RT is the CRA program identifier for GST/HST accounts. Other identifiers cover payroll (RP), corporation income tax (RC) and more.
What does the 0001 mean?
It is the 4-digit reference number that tells apart accounts of the same type under one business number. 0001 is the first.
How do I check that a supplier's GST/HST number is real?
Use the CRA's GST/HST Registry. This tool only checks the shape of the number and never contacts the CRA.
Format only, not a register lookup
This tool tests the structure of the number in your browser. It does not query any register, and a passing result does not show the number was issued or is still active. To confirm that, confirm a GST/HST account on the CRA GST/HST Registry. Nothing you type is transmitted, stored or logged.