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Australian ABN Checker
Australia has GST rather than VAT, and businesses are identified by an eleven-digit Australian Business Number (ABN). There is no separate GST number: a business registers for GST against its ABN.
This checker asks the Australian Business Register (ABN Lookup) whether the ABN is active and whether it is registered for GST — two different questions, because a business can hold an active ABN without being registered for GST.
Checked live against the Australian Business Register (ABN Lookup). Not affiliated with the Australia tax authority.
Australia VAT number format
- Local name
- ABN (Australian Business Number)
- Structure
- 11 digits
- Format example
- 18 123 456 789Illustrative: right shape and check digit, not a registered business.
- Standard rate
- 10%
Eleven digits, usually written 12 345 678 901. There is no country prefix in Australia; AU is accepted and ignored. The first two digits are check digits, verified here with the ABN modulus-89 algorithm.
How this Australia check works
- Format, in your browser. As you type, the number is compared with the Australia pattern and its check digit is recomputed. This costs nothing and sends nothing: a number in the wrong shape is rejected on the spot and never reaches the registry.
- Registration, live. A well-formed number is then looked up in the Australian Business Register (ABN Lookup), which says whether it is registered today and, where the register publishes them, the business name and address. Free checks are limited per visitor per hour so the registry is not scraped through this page.
- More checks, or from your code. A free account gives you an API key with 100 validations a month, the same answer as this page as JSON.
What usually goes wrong
Sending an ACN
An Australian Company Number has nine digits and identifies a company with ASIC. A company's ABN is often its ACN with two check digits in front, but the ACN alone is not an ABN.
Assuming an active ABN means GST registration
Businesses below the GST registration threshold can hold an ABN without being registered for GST. Check the GST status, not only the ABN.
Frequently asked questions
Is an ABN a VAT number?
It is the closest equivalent. Australia's GST is registered against the ABN, so the ABN is what you collect from an Australian business customer.
What is the difference between an ABN and an ACN?
The ACN is a nine-digit company number from ASIC. The ABN is an eleven-digit business number from the ATO's register, and sole traders and trusts have one too.
Does the check show GST registration?
Yes, as far as the register shows it: the result says whether the ABN is active and whether ABN Lookup reports a GST registration against it.
Validating Australia numbers from your own code instead of by hand? The Australia VAT validation API guide has the endpoint, the response shape and examples in four languages. To check a number from another country, go back to the VAT number checker.