When you register a business name, you must provide an ABN or ABN reference number.

An ABN is a unique 11 digit number that identifies your business to the government and community. It doesn’t replace your tax file number.

You can register a business name at the same time as your ABN application if you use the Business Registration Service. If you don’t, you’ll need to go back to the Business Registration Service to register your business name.

To apply for an ABN, register a company or business name, and apply for the tax registrations you need.

https://register.business.gov.au/registration/type