Free Australian business tools
ABN format checker
Check the format and checksum of an Australian Business Number, then verify the business and GST registration in official ABN Lookup.
Checks the mathematics of the number only. It confirms the digits are self-consistent — it does not tell you who the number belongs to or whether the business is registered for GST. For that, use the government register at ABN Lookup.
A useful first check, with a clear limit.
An ABN contains 11 digits with a mathematical checksum. This tool checks that format locally. A passing result does not prove that the number is registered, belongs to a business or has active GST registration.
Follow the result link to official ABN Lookup to check the entity and registration dates. The method is described by the Australian Business Register.