The Australian business number (ABN) is a single business identifier that allows businesses to deal with the Australian Taxation Office (ATO) and other government departments and agencies with one identifier. An ABN is not compulsory and not everyone is entitled to an ABN. The following entities will need an ABN to comply with other tax obligations:

Businesses use activity statements to report and pay a number of tax obligations, including GST, pay as you go (PAYG) instalments, PAYG withholding and fringe benefits tax. Non-business individuals who need to pay quarterly PAYG instalments also use activity statements. Activity statements are personalised to each business or individual to support reporting against identified obligations.