Australian ABN Checksum Validator

How Australian ABN Checksum Validator Works?

The Australian ABN Checksum Validator works by subtracting 1 from the first digit of the 11-digit Australian Business Number (ABN), multiplying the digits by weights 10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, and confirming the sum is divisible by 89.

1. 1Remove spaces and confirm 11 digits.
2. 2Subtract 1 from the first digit.
3. 3Multiply each digit by its weight: 10, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19.
4. 4Add the products.
5. 5Mark the ABN valid when the sum mod 89 = 0.

Australian ABN Checksum Validator Formula

The ABN formula is ((d₁ − 1)·10 + Σ dᵢ·wᵢ) mod 89 = 0.

S = (d₁ − 1)·10 + d₂·1 + d₃·3 + d₄·5 + d₅·7 + d₆·9 + d₇·11 + d₈·13 + d₉·15 + d₁₀·17 + d₁₁·19
valid ⇔ S mod 89 = 0

• d₁d₂ are the 2 check digits at the front of the ABN.

Subtract 1 from first digit: 41824753556
4×10 + 1×1 + 8×3 + 2×5 + 4×7 + 7×9 + 5×11 + 3×13 + 5×15 + 5×17 + 6×19 = 534
534 mod 89 = 0 → valid

Australian ABN Checksum Validator Conversion Table

The ABN validation table lists sample ABNs with their weighted sum and result.

What is Australian ABN Checksum Validator?

An Australian ABN Checksum Validator is a tool that checks the modulus 89 checksum of an 11-digit Australian Business Number. The Australian Business Register (ABR) issues ABNs.

An ABN is built from a 9-digit ACN or other identifier with 2 leading check digits. A valid checksum confirms the format only; the ABN Lookup service confirms registration.

What are the uses of Australian ABN Checksum Validator?

There are 3 main uses of the Australian ABN Checksum Validator, including tax invoices, supplier onboarding, and withholding rules.

• Tax invoices: Businesses confirm ABNs on invoices for GST credit claims.
• Supplier onboarding: Accounts payable teams check supplier ABNs.
• Withholding rules: Payers withhold 47% from suppliers who quote no valid ABN.