Validate or calculate the check digit for any Australian Company Number using the official ASIC algorithm — runs entirely in your browser.
For official company searches including name, status, and registered address, visit ASIC at connectonline.asic.gov.au.
The ACN Check Digit Validator instantly verifies whether an Australian Company Number is valid, or calculates the correct ninth digit from the first eight — all using the official ASIC algorithm, right in your browser.
Every company registered with the Australian Securities and Investments Commission (ASIC) under the Corporations Act 2001 is issued a unique 9-digit ACN. The last digit is a modulus-10 weighted check digit derived from the preceding eight, so a single typo in an ACN is easy to catch mathematically — no database lookup required. This tool puts that check at your fingertips, whether you are confirming a number is genuine or generating a valid one for testing. People rely on it to:
Because all calculation runs locally, nothing you type is ever uploaded — the numbers you check stay entirely on your device. Remember that a valid check digit only proves a number is well-formed, not that the company exists or is active; for official company name, status, and registered-address details, follow the link to ASIC Connect.
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.
Multiply each of the first eight digits by the weights 8, 7, 6, 5, 4, 3, 2 and 1 in order, then add the products together. Take that total modulo 10 and subtract the remainder from 10. If the result is 10, the check digit is 0. The final value is the ninth digit of a valid ACN.
An ACN is a 9-digit number issued by ASIC that identifies a registered company. An ABN is an 11-digit Australian Business Number issued by the ATO to any entity carrying on a business, including sole traders and trusts. A company's ABN is formed by adding two leading check digits to its existing ACN, so the last nine digits of a company ABN are its ACN.
An ACN always has exactly nine digits. It is conventionally displayed in three groups of three, for example 123 456 789, which makes it easier to read and transcribe. This tool formats it that way automatically.
Not exactly, but they are closely linked. A company keeps its 9-digit ACN for life, and its 11-digit ABN is built directly from it by prepending two check digits. So a company has both numbers, and you can recognise its ABN because the trailing nine digits match its ACN.