AUSTRALIAN TOOLS
ABN Validator.
Validate Australian Business Numbers with the official ATO checksum algorithm.
ATO Format Check
This validates ABN format only. Check ABN Lookup (abr.business.gov.au) for active status.
Three simple steps
How to use ABN Validator
1
Enter ABN
Type or paste the 11-digit ABN.
2
Validate
Run the ATO checksum algorithm instantly.
3
Read result
See valid/invalid status and formatted ABN.
Helpful answers
Frequently asked questions
How is an ABN checked for validity?
Subtract 1 from the first digit, multiply the 11 digits by the weights 10,1,3,5,7,9,11,13,15,17,19 and sum them. If the total divides evenly by 89, the ABN is valid.
Does this tool tell me if an ABN is currently registered?
No. It validates the number format offline. For live registration status, GST registration and the trading name, use the government's ABN Lookup service.