Australia ABN Generator
Online generator for Australian Business Number (ABN) issued by the ATO for software testing and invoicing QA.
Waiting for generation...
About the Australian Business Number (ABN)
The Australian Business Number (ABN) is a unique 11-digit identifier issued by the Australian Taxation Office (ATO) and registered in the Australian Business Register (ABR).
It identifies businesses, sole traders, partnerships, and government entities for tax invoices, Goods and Services Tax (GST) reporting, and commercial transactions across Australia.
ABN Calculation and Validation Algorithm (Weighted Modulo 89)
The official Australian Taxation Office (ATO) algorithm applies positional weights and modulo 89 division:
Sum = (d₁ - 1) × 10 + d₂ × 1 + d₃ × 3 + d₄ × 5 + d₅ × 7 + d₆ × 9 + d₇ × 11 + d₈ × 13 + d₉ × 15 + d₁₀ × 17 + d₁₁ × 19; Valid if Sum mod 89 = 0
- Subtract 1 from the first digit of the 11-digit number.
- Multiply each digit by its respective weight [10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19].
- Sum all resulting products together.
- The ABN is mathematically valid if the total sum is divisible by 89 with zero remainder.