- This tells you whether the number is correctly formed. It cannot tell you whether the CRA registered it, or to whom.
🔒 Your number never leaves this page. The check runs in your browser: nothing is sent, stored or logged, and there is no account.
Parts of the number
A Business Number identifies a business with the CRA. Each program account adds a program identifier and a reference number.
Business Number
Nine digits. The ninth is a check digit worked out with the same Luhn method used for Social Insurance Numbers.
Program identifier
Two letters that say which program the account is for, such as RT for GST/HST.
Reference number
Four digits that tell apart several accounts of the same type under one Business Number.
The method is described in the CRA’s sheet “Validation of Social Insurance Numbers”, which says it applies to Business Numbers too. The copy we link to is an archived 2006 capture of a 2002 document.
Program identifiers
From the CRA’s page on whether you need a program account.
| Identifier | Program |
|---|---|
| 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/export (administered by the CBSA since October 21, 2024) |
| RN | Insurance premium tax |
| LT | Luxury tax |
| RU | Underused housing tax |
| PT | Global minimum tax |
Frequently asked questions
Is the number I type sent anywhere?
No. The check is a few lines of JavaScript on this page. Nothing is sent, stored or logged.
Does a pass mean the business is registered?
No. It means the nine digits are consistent with each other. The CRA is the only source that can confirm a registration, and a random nine-digit string passes about one time in ten.
Is a Business Number the same as a GST/HST number?
The GST/HST account number is the Business Number plus RT and a reference number, for example 123456789 RT 0001. The nine digits are the Business Number itself.
What if my program identifier is not recognised?
We follow the CRA’s program account page as of November 1, 2026. If you hold an account with a newer identifier, the checksum result is still valid for the nine digits.
Why does the reference number matter?
A business can have several accounts of the same type, such as more than one payroll account. The reference number tells them apart; it is usually 0001 for the first.
Last updated
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How we check it
The checksum is tested on the CRA sheet’s worked example, 999 999 998 (doubled digits 36, other digits 36, total 72, next ten 80, check digit 8), and compared with a separate digit-splitting Luhn implementation on 20,000 pseudo-random nine-digit strings.
Program account parsing is tested on several writings of the same number (with or without spaces, hyphens or lowercase), on malformed program parts and on all thirteen identifiers in the table above.
Limits: no CRA service is called, so a pass cannot show that a number is registered. The CRA checksum sheet is an archived document that we could not match against a current version. The identifier table is a copy of the CRA page as reviewed, and we did not verify that every identifier has an open account type today.