The Australian Business Number (ABN) is an 11-digit number issued by the Australian Taxation Office to identify a business for tax and dealings with government. Unlike the ACN (which only companies have), an ABN can be issued to any business structure: company, sole trader, partnership, trust.
What it's used for
- GST registration (a business with GST turnover of A$75k+ must register)
- Invoicing — invoices without an ABN trigger withholding tax
- Identifying counterparties for due diligence
- Looking up trading names, GST status, and ABN history via the ABR
ABN ≠ ACN
For a company, the ABN is usually two digits + the 9-digit ACN. But not all ABNs map to ACNs (sole traders don't have ACNs). Don't assume the conversion.
The ABR
Lookups happen via the Australian Business Register — a free public service operated by the ATO. We mirror it through a friendlier API.
Related terms
- ACN — A unique 9-digit number assigned by ASIC to every Australian company at registration.
- ABR — The free public register of ABNs, GST registration, and trading names, operated by the ATO.
How Hoist Assets uses this
Search the ABN via the Hoist Assets API or MCP server. See /docs for endpoints.