Validate any Australian Business Number using the official ATO check digit algorithm — instantly, in your browser, with no data sent anywhere.
This tool validates the ABN format and check digit only. To look up the registered business name or details, visit the Australian Business Register at abr.gov.au.
ABN Validator instantly checks whether an Australian Business Number is structurally valid, applying the official ATO check digit algorithm to all 11 digits — right in your browser, with nothing sent to a server.
An ABN is the 11-digit identifier the Australian Business Register (ABR) issues to every registered business entity. Because the last digits are mathematically linked to the rest of the number, a single typo can be caught immediately rather than slipping into your accounts. People reach for this tool to:
Because every check runs locally, you can paste sensitive supplier or client numbers without them ever leaving your device. A green tick confirms the number is mathematically correct, while a red cross flags a check digit that does not match.
Keep in mind that passing validation only proves the number is well-formed — it does not confirm the business is currently active or GST-registered. For that, follow the ABR lookup link to abr.gov.au, the only authoritative source for live registration details.
An ABN (Australian Business Number) is a unique 11-digit identifier issued by the Australian Business Register to each business entity. Any business with a turnover of $75,000 or more must register for one.
The ATO algorithm subtracts 1 from the first digit, multiplies each of the 11 digits by the weighting factors [10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19], and checks the sum is divisible by 89.
No. It's an independent tool that implements the publicly documented ATO algorithm. A pass here means the number is mathematically correct — always confirm active registration via the ABR at abr.gov.au.
Type or paste the 11-digit number into the box above. The tool applies the official check digit algorithm and shows a green tick for a valid number or a red cross for one that fails. To confirm the business is also active and GST-registered, follow the ABR lookup link.
An ACN (Australian Company Number) is a 9-digit number issued by ASIC to registered companies only. An ABN is an 11-digit number issued by the ABR to any business entity, including sole traders and partnerships. For companies, the ABN is usually the 9-digit ACN with two extra leading check digits.
An ABN is always exactly 11 digits, often written in a 2-3-3-3 grouping such as 51 824 753 556. The first two digits are check digits derived from the remaining nine, which is what lets this tool detect a mistyped number.
No. This is an independent tool and is not affiliated with the government. It validates the format and check digit offline, then offers a link to the official Australian Business Register at abr.gov.au, where you can verify live registration and business details.