An Australian Business Number (ABN) is an 11-digit unique identifier issued by the Australian Business Register (ABR). It identifies a business to the ATO, other government agencies, and other businesses in a standard format across all states and territories.
Why you need an ABN
- Register for GST (required if turnover meets the threshold).
- Claim GST input tax credits.
- Register a business name through ASIC.
- Avoid the no-ABN withholding rule — without quoting an ABN, a business or individual paying you is required to withhold 47% of the payment and remit it to the ATO.
- Access government grants and online services.
ABN vs ACN
An ABN is not the same as an ACN (Australian Company Number). A company registered with ASIC has a 9-digit ACN; its ABN is derived by adding a two-digit check prefix to the ACN. Sole traders, partnerships and trusts have ABNs but not ACNs.
Verifying an ABN
Anyone can check an ABN's status, associated entity name, ABN type, and GST registration date via ABN Lookup (abr.business.gov.au) — a free public register. Accountants should verify ABNs on supplier invoices before processing input tax credits.
Can I have more than one ABN?
Generally, one ABN per legal entity. However, a person can operate separate businesses as a sole trader and also have ABNs for trusts or partnerships they are involved in — each entity has its own ABN.