What is an ABN?
An Australian Business Number (ABN) is a unique 11-digit identifier issued by the Australian Business Register (ABR), which is operated by the Australian Taxation Office (ATO). Introduced on 1 July 2000 as part of major tax reforms, the ABN simplifies how businesses interact with government agencies and other businesses across Australia.
The ABN is a public number and does not replace your Tax File Number (TFN). It appears on tax invoices, business correspondence, and other commercial documents, making it easier for buyers to identify suppliers and for the ATO to manage tax obligations.
Who needs an ABN?
Almost all businesses — whether sole traders, partnerships, companies, or trusts — that carry on an enterprise in Australia are required to have an ABN. You may be entitled to an ABN if you:
- Are carrying on a business or enterprise in Australia
- Make sales connected with Australia in the course of running an enterprise
- Are a company registered under the Corporations Act 2001
Why is an ABN important?
Quoting your ABN on invoices and business documents is critical. If you supply goods or services to another business without quoting an ABN, that business may be required to withhold 47% of the payment and send it to the ATO under the Pay As You Go (PAYG) withholding system.
Your ABN is also required to register for GST, claim GST credits, and lodge Business Activity Statements. A single ABN can be used across multiple business activities, provided they all operate under the same business structure. If you run a second business under a different structure, you’ll need to apply for a separate ABN.