Australian Company Number digit check

The Australian Company Number (ACN) is a nine digit number with the last digit being a check digit calculated using a modified modulus 10 calculation.

ASIC has adopted a convention of always printing and displaying the ACN in the format XXX XXX XXX; three blocks of three characters, each block separated by a blank. This is to assist readability and the inserted blanks do not form part of the ACN.

How we validate Australian Company Numbers

For example, to validate the check digit for ACN 004 085 616:

Step 1 - Apply weighting to digits 1 to 8.

Digit	0	0	4	0	8	5	6	1
Weight	8	7	6	5	4	3	2	1
Digit X Weight	0	0	24	0	32	15	12	1

Step 2 - Sum the products

In this example, it would be 0 + 0 + 24 + 0 + 32 + 15 + 12 + 1 = 84

Step 3 - Divide by 10 to obtain remainder

In this example, 84 / 10 = 8 remainder 4

Step 4 - Complement the remainder to 10

In this example, 10 - 4 = 6

If the complement equals 10, set it to 0.

Based on these calculations, the calculated check digit (6) equals the check digit (6) so ACN 004 085 616 is VALID.

Examples of valid ACNs include:

000 000 019	000 250 000	000 500 005	000 750 005
001 000 004	001 250 004	001 500 009	001 749 999
001 999 999	002 249 998	002 499 998	002 749 993
002 999 993	003 249 992	003 499 992	003 749 988
003 999 988	004 249 987	004 499 987	004 749 982
004 999 982	005 249 981	005 499 981	005 749 986
005 999 977	006 249 976	006 499 976	006 749 980
006 999 980	007 249 989	007 499 989	007 749 975
007 999 975	008 249 974	008 499 974	008 749 979
008 999 979	009 249 969	009 499 969	009 749 964
009 999 964	010 249 966	010 499 966	010 749 961

Note that Australian Registered Body Numbers (ARBNs) and Australian Registered Scheme Numbers (ARSNs) are constructed using the same formula.