Free ABN Lookup
Validate any Australian Business Number instantly. Check registration status, GST registration, and business details from the ABR registry.
Enter the 11-digit ABN. Format: XX XXX XXX XXX
Create a tax invoice with your ABN
Auto-fill your ABN and GST details into a professional invoice.
What is an ABN?
An Australian Business Number (ABN) is an 11-digit identifier issued by the Australian Business Register (ABR) to businesses operating in Australia. It's required for businesses to invoice for goods and services, register for GST, and claim tax credits.
How ABN Validation Works
ABN validation uses a weighted checksum algorithm. The first digit is reduced by 1, then each digit is multiplied by a weight (10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19). The sum must be divisible by 89 for the ABN to be valid.
When Do You Need an ABN on an Invoice?
If you're registered for GST, you must include your ABN on all tax invoices. If you're not registered for GST, you should still include your ABN on invoices over $75 so clients can claim input tax credits.