Is an ABN mandatory?

It is not compulsory to have an Australian business number (ABN). However, an ABN enables a business to deal with a range of government departments and agencies using the one unique identification number. It is also an essential component for business to operate within the goods and services tax (GST) system.

You can also use your ABN when dealing with other businesses. For example, you generally need to quote your ABN on invoices you give to other businesses to avoid having them withhold tax from payments they make to you. If you are registered for GST, you will need to put your ABN on your invoices to make them ‘tax invoices’.