Company number
Enter the nine digits, with or without spaces.
Your ACN check
Example inputsUnavailable. Check the message beside your input.
- Passes checks
The ninth digit matches the check digit calculated from the first eight digits.
- 004 085 616
- Matches
How the ACN Check Digit Works
The last digit of an Australian company number (ACN) is calculated from its first eight digits. The Australian Securities and Investments Commission (ASIC) publishes the ACN check-digit calculation in Appendix B of its Datastream specification.
- Multiply the first eight digits by the weights 8, 7, 6, 5, 4, 3, 2 and 1, in that order.
- Add those products and find the remainder after dividing the total by 10.
- Subtract the remainder from 10. If the answer is 10, use 0.
- Compare the calculated digit with the ninth digit entered.
ASIC’s example is 004 085 616. Its weighted products total 84, leaving a remainder of 4. The calculated digit is 6, which matches the number’s last digit. Entering 004 085 617 instead fails the checksum.
Formatting and Transcription Errors
The checker accepts nine digits with or without spaces and keeps leading zeros. Its formatted result groups the digits into three blocks, such as 004 085 616.
| Entry | Result |
|---|---|
| 004085616 or 004 085 616 | Passes format and checksum |
| 004 085 617 | Nine digits, but the check digit does not match |
| 04085616 | Too short: the leading zero is missing |
| 004 O85 616 | Contains the letter O instead of a digit |
For a failed check, compare the whole number with the original document. A checksum failure does not identify which digit was copied incorrectly. Replacing only the final digit could create a different number.
Checksum Versus Company Registration
A passing checksum establishes that the digits satisfy the formula. It does not establish that ASIC issued the number, that a company remains registered or that it belongs to your client.
Use ASIC’s company and organisation register search to match the number to the company’s name and registration details. The browser checker performs no register lookup and returns no company status.
ACN and ABN Are Different Identifiers
An ACN has nine digits. An Australian business number (ABN) has 11 digits and uses a different checksum.
ABN Lookup’s published formula uses all 11 digits and division by 89. An 11-digit ABN fails this checker’s length requirement. Keep the identifier supplied for your task and validate it using its own formula.