Australia · ABN
Australian ABN Checker
Check an Australian Business Number for correct format and check digits, and confirm it in the ABN register — with the entity name, type, state and status.
What is an ABN?
An Australian Business Number (ABN) is the 11-digit public identifier issued to businesses registered in the Australian Business Register — for example 28 008 984 049 for Wesfarmers Limited. It is used on invoices and in dealings with the ATO, and a company’s ABN is often its 9-digit ACN with two check digits in front.
Australian ABN format
Two check digits and nine digits — for a company, often its ACN.
(mod 89)
(often the ACN)
Example: 28 008 984 049 (Wesfarmers Limited, ACN 008 984 049).
- 11 digits: Usually printed as 2-3-3-3 with spaces. Digits only, no letters.
- Check digits: The ABR’s published mod-89 algorithm. A mistyped digit almost always fails it.
- Branches: A GST branch has its own registration number that incorporates the parent’s ABN; enter the 11-digit ABN on its own.
- Not shown: The checker does not show GST registration, and a cancelled ABN shows as no matching record.
How to check an ABN
- 1 Find the ABN on the supplier’s tax invoice or website.
- 2 Enter the 11 digits above. The checker runs the check-digit algorithm and confirms the ABN in the register.
- 3 Compare the returned entity name, type and state with your supplier.
- 4 Need GST status or the full record? Our ABN verification guide walks through ABN Lookup step by step.
Frequently Asked Questions
How do I check an ABN?
Enter the 11 digits in the checker on this page: it runs the official ABN check-digit algorithm, then confirms the ABN in the register and shows the entity name, type, state and status. For GST status and the full ABN Lookup record, see our ABN verification guide.
How is the ABN check digit calculated?
Subtract 1 from the first digit, multiply the 11 digits by 10, 1, 3, 5, 7, 9, 11, 13, 15, 17 and 19, and add the results. A valid ABN gives a total divisible by 89 — the method published by the Australian Business Register.
What is the difference between an ABN and an ACN?
The ACN is the 9-digit number ASIC gives a company when it registers. A company’s ABN is often its ACN with two check digits in front — Wesfarmers Limited’s ACN 008 984 049 becomes ABN 28 008 984 049. Sole traders, partnerships and trusts have an ABN but no ACN.
Is there a separate GST number in Australia?
No. GST registration is recorded against the business’s ABN, and ABN Lookup shows whether and from when the business is registered for GST. Our checker confirms the ABN but does not show GST status.
What happens if a supplier doesn’t quote an ABN?
A business paying more than A$75 (excluding GST) to a supplier who does not quote an ABN generally has to withhold 47% of the payment and send it to the ATO.
Is a TFN the same as an ABN?
No. The Tax File Number is a confidential tax identifier held by individuals and by entities such as companies and trusts, and should be kept confidential, not shown publicly. The ABN is a public business identifier listed in ABN Lookup.
Last reviewed: , against official sources.
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Check Australian ABNs and tax IDs from 100+ countries in one API call — with registered entity details.