An ACN (Australian Company Number) is a unique 9-digit number issued by ASIC to every registered company in Australia.

How does the ACN check digit work?

The first 8 digits are multiplied by weights [8,7,6,5,4,3,2,1] and summed. The sum mod 10 is subtracted from 10 (10 becomes 0) to produce the check digit.

What is the difference between an ACN and an ABN?

An ACN identifies a registered company under the Corporations Act. An ABN is a broader identifier issued by the ATO; a company's ABN is derived by prepending two check digits to its ACN.

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ACN Check Digit Validator

Validate or calculate the check digit for any Australian Company Number using the official ASIC algorithm — runs entirely in your browser.

Enter ACN (9 digits)

0 / 9 digits

Formatted ACN

click to copy

Check digit

For official company searches including name, status, and registered address, visit ASIC at connectonline.asic.gov.au.

How to use

Pick a mode — validate a full 9-digit ACN or compute the check digit from the first 8 digits.
Type or paste the digits. Spaces and dashes are stripped automatically.
Click the formatted ACN to copy it, or follow the ASIC link to look up the company.

FAQ

An Australian Company Number is a 9-digit identifier ASIC assigns to every company registered under the Corporations Act 2001. It must appear on all official company documents.

Multiply the first 8 digits by the weights 8, 7, 6, 5, 4, 3, 2, 1 and sum them. Take the sum modulo 10 and subtract from 10 (use 0 if the result is 10). The result is the valid 9th digit.

No. An ACN identifies a company under ASIC; an ABN is broader and issued by the ATO for any business. A company's ABN is derived by prepending two check digits to its ACN.