An Australian Company Number (usually shortened to ACN) is a unique nine-digit number issued by the Australian Securities and Investments Commission (ASIC) to every company registered under the Commonwealth Corporations Act 2001 as an identifier. The number is usually printed in three groups of three digits. It must be quoted on all correspondence and invoices issued by that company. A similar system is used for non-company entities such as trusts, and for foreign companies.


Under the Corporations Act 2001, every company in Australia is issued with a unique, nine-digit number, an Australian Company Number (ACN). Companies are required to disclose their ACN on: the common seal (if any) and every other seal of the company (if any); every public document issued, signed or published by, or on behalf of, the company; every eligible negotiable instrument issued, signed or published by, or on behalf of, the company; and all documents required to be lodged with ASIC. An ACN is not required on (at least): packaging and labelling, including envelopes and transport documents; advertisements which do not make a specific offer which is capable of being accepted (such as advertisements which only promote the company and its goods or services in general); credit cards and credit card vouchers; machine-generated receipts, including cash-register receipts; business cards and 'with compliments' slips; and items which are not documents (e.g., vehicles, television advertisements). An ACN remains unchanged even if a company has a name change or is deregistered. A similar 9 digit (ARBN) is used for non-company entities such as registerable Australian bodies, and for foreign companies.

Progression to ABN

When the Goods and Services Tax (Australia), GST was introduced in Australia the government also introduced a number of complementary measures. These included the ABN, removal of wholesale Sales Tax exemptions and changes to the Fringe benefits tax (Australia), FBT and changes to the treatment of trusts and charities. A company's Australian Business Number (ABN) frequently includes the ACN as the last nine digits. The ABN indicates that a person, trust or company is registered with the Australian Business Register (ABR). The ABR facilitates and streamlines many Australian business-to-government and government-to-business processes, such as Australian Tax Office transactions involving the collection and remittance of the Goods and Services Tax (Australia), Goods and Services Tax (Goods and Services Tax (Australia), GST).


* ACN 000 000 019, 007 249 989, 005 749 986 * ABN 53 004 085 616{{cite web , title=Format of the Australian Business Number (ABN) , url=https://softwaredevelopers.ato.gov.au/sites/default/files/resource-attachments/Format_of_the_Australian_Business_Number_%28ABN%29.docx , website=Australian Taxation Office , accessdate=3 December 2018

Number generation

The ACN is generated using an algorithm with the last digit being
check digit
allowing the number to be verified. The ABN is generated using an algorithm where the first two digits are check digits, se

The last 9 digits of an ABN do not always comply with the ASIC ACN algorithm, for example the Australian Tax Office ABN 51 824 753 556.

Purpose of ACNs and ABNs

Prior to the introduction of the 9 digit ACN, company information was filed under the company name, which might vary from 1 to 80 characters. This is an inefficient way to run a filing system, and can lead to problems, particularly if two company names differ in one of the middle letters, for example: Strudle Pty Ltd and Stradle Pty Ltd. Unique identifiers, like the ACN, help reduce fraud by firstly clearly differentiating companies and/or subsidiaries with similar names, since companies with similar names will tend to have completely different ACNs. Also if a company changes its name for any reason, including phoenix company, the ACN remains the same.

Other countries

* Cambodia ** C/O 2456/096 - The Railways Transport Co-operation (RTC Co. Ltd.) * Canada ** The CA Identification Number is used in Canada to identify textile dealers. * Brazil ** CNPJ * United Kingdom - Registered number. ** company number 00037038 - The Equitable Life Assurance Society * United States ** Registered Identification Number


External links

Australian Business Register

Australian Company Numbers from ASICCompany Registration in Australia
Company 123 Pty Ltd - Third party online company registration company Taxation in Australia Company identification numbers Companies of Australia Australian Securities and Investments Commission