How is a Canadian Business Number validated?

The 9-digit BN root carries a trailing check digit that satisfies the Luhn (mod 10) algorithm — the same scheme used by credit cards. The tool applies Luhn to all 9 digits and confirms the total is divisible by 10.

What is the RT 0001 part?

After the 9-digit BN, the CRA adds a 2-letter program identifier and a 4-digit reference to form a program account: RT for GST/HST, RP for payroll, RC for corporate income tax, RZ for information returns, and RM for import/export.

Does a valid check digit mean the business is registered?

No. A valid check digit confirms the number is internally consistent. It does not confirm the business is registered or that the GST/HST account is active — use the CRA's GST/HST Registry to confirm that.

Why is my BN failing?

A Luhn failure almost always means a digit was mistyped or transposed. Re-check the 9 digits against the source. A single wrong digit breaks the check.

Is my Business Number sent anywhere?

No. The Luhn check and suffix parsing run entirely in your browser. Nothing is uploaded.

Canada Business Number Validator

A Canadian Business Number (BN) is the 9-digit identifier the Canada Revenue Agency (CRA) assigns to every business. Each tax program — GST/HST, payroll, corporate income tax — extends the BN with a 2-letter program identifier and a 4-digit reference to form a program account such as 123456789 RT 0001. This free validator checks the 9-digit root with the official Luhn check digit and parses any program-account suffix, which is useful for accounts-payable, GST-refund and supplier-onboarding workflows.

How it works

The 9-digit BN root ends in a Luhn (mod 10) check digit:

Take the 9 digits. Starting from the rightmost digit, double every second digit.
If doubling produces a two-digit number, subtract 9 (equivalently, add its digits).
Sum all the resulting digits.
The BN is valid if the total is divisible by 10.

If a suffix is present, the tool confirms the 2-letter program identifier is one of RT, RP, RC, RZ or RM, and that the reference is 4 digits.

Example

For 123456789, applying Luhn over the digits gives a total that is checked against mod 10. Append RT 0001 and the validator additionally reports the program type as GST/HST with reference 0001.

Notes

A valid result means the number is well-formed, not that the account is open or active. To confirm a GST/HST registration is live, use the CRA’s official GST/HST Registry. Everything here runs locally in your browser.