ABN Validator
Check an ABN or ACN for length and check-digit errors, with the number kept on your device.
Business identifier
11 digits. Spaces are accepted. The starting number is the ABR's published example.
9 digits. Keep leading zeroes. The starting number is ASIC's published example.
Check result
Check-digit result
Valid arithmetic
Registration status is not checkedNormalised number
51 824 753 556
Spaces added for readabilityAdjusted weighted total 534. Remainder after division by 89: 0. Passes the ABN arithmetic test.
This checks number length and arithmetic. It does not confirm a legal entity name, active registration or GST status. Your entries stay in this browser.
ABN Check-Digit Method
An ABN passes the published arithmetic test when its adjusted weighted total has a remainder of zero after division by 89. This ABN validator accepts 11 digits with optional spaces. Letters and punctuation produce an input error.
The Australian Business Register's ABN method subtracts one from the first digit. It then multiplies the digits, from left to right, by 10, 1, 3, 5, 7, 9, 11, 13, 15, 17 and 19. Add the products and divide by 89.
In the ABR's published example, 51 824 753 556 gives a weighted total of 534. That is six times 89, with remainder zero. Changing the final digit to 7 gives 553 and remainder 19, so 51 824 753 557 fails.
A Valid Number is Not a Registry Result
A check-digit pass confirms that the entered digits satisfy the arithmetic rule. It cannot establish whether a business exists or whether its registration is active. It also cannot confirm the entity's legal name or GST status.
Before relying on an identifier in a loan file, match the original document against the registry record. Use ABN Lookup to check the recorded entity and its registration details. This tool sends no entered identifier to that service.
ACN Validation
An ACN is a nine-digit company identifier with its own check-digit method. Select ACN mode to use the ACN validator. Leading zeroes form part of the number, so enter 004 085 616 with both initial zeroes.
ASIC's EDGE specification, Appendix D, weights the first eight digits by 8 through 1. The expected final digit is the complement of the total's remainder after division by 10. A complement of 10 becomes 0.
ASIC's example 004 085 616 has a weighted total of 84. Its remainder is 4, so the expected final digit is 6. The entered final digit matches. Some different numbers share the same check digit. An ACN arithmetic pass gives no company registration result.