What is the Australian Business Number (ABN)?

The Australian business number (ABN) is a unique 11 digit identifier that makes it easier for businesses and all levels of government to interact.

When will you use your ABN?

Examples of when you may need to use your ABN include:

when dealing with the Tax Office (the ABN is quoted as a reference)
in the future, when dealing with other government agencies subsection 3(1) A New Tax System (Australian Business Number) Act 1999
so that other businesses will not withhold tax at the top marginal rate from payments they make to you
when supplying goods and services to other businesses (and other entities carrying on enterprises).
to register for goods and services tax (GST) and to claim input tax credits and fuel tax credits (FTC)
if you want to be endorsed as a deductible gift recipient and/or you want to be endorsed as a tax concession charity or income tax exempt fund, and
to account for or offset your taxation obligations on an activity statement.