ACN and ABN: which is which
The ACN (Australian Company Number) is nine digits, issued by the corporate regulator ASIC when a company is registered, and only companies have one. The ABN (Australian Business Number) is eleven digits, issued through the Australian Business Register for dealings with government and tax, and any business can hold one: companies, sole traders and partnerships alike.
For a company, the two connect arithmetically: the ABN is the ACN with two leading check digits, so the last nine digits of a company's ABN should be exactly its ACN. An "ABN" and "ACN" on the same paperwork that do not reconcile this way belong to different entities, a discrepancy to resolve before you do business.
How to check an ABN or ACN free
ABN Lookup, the government's free register, returns the entity behind any ABN: legal name, entity type, GST registration and status, current and historical. ASIC's registers confirm company details behind an ACN. Together the two checks take under a minute and cost nothing.
For routine vetting, confirm the ABN is active, the entity type matches what you were told (a "company" that resolves to a sole trader's ABN is a question), and GST registration fits the size of business claimed. The wider sources are on our Australia company credit report page and in the registry directory.
What the numbers prove, and what they don't
An active ABN with the right entity type confirms registration and tax standing; it does not confirm solvency, payment record or litigation, and Australian private companies publish little financially. Before a commercial business decision, a full company report adds what the numbers cannot show: financial standing, payment behaviour and adverse history.
Common questions
Does every Australian business have an ACN?
No. Only registered companies have an ACN. Sole traders and partnerships operate with an ABN alone, which is why the entity type returned by ABN Lookup matters as much as the number being active.
How do ABN and ACN relate for a company?
A company's ABN is its ACN plus two leading check digits, so the last nine digits of the ABN should equal the ACN exactly.
How do I check an Australian business for free?
Search the ABN on ABN Lookup for the entity, status and GST registration, and the ACN on ASIC's registers for the company details.
Need more than the number can tell you?
An Australia company credit report adds financial standing, payment behaviour and adverse history to the registry facts. Delivered in plain English.