Australian Business Number

An Australian Business Number, or ABN, is an 11 digit unique identifier issued by the Australian Taxation Office (ATO) that is used by business entities when dealing with the Australian government. It was introduced as part of the New Tax System brought in by John Howard's Liberal government on 1 July 2000 as part of the Goods and Services Tax.

The ABN is an eleven digit number where the first two digits are check digits. Unlike with the TFN, the ATO has publicised the formula for checking and creating valid ABN checksums. Also, the nature of the ABN algorithm means that any 9 digit number can be made into a valid ABN.

In the case of companies, the ATO determines the ABN by using the company's Australian Company Number (ACN) to which is prefixed the two-digit checksum.

See also

• Australian Company Number

External links

• Australian Business Register
• ABN Lookup
• Format of the ABN

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