Under the Corporations Act 2001, every company in Australia has been issued with a unique, nine-digit number, an Australian Company Number (ACN), which must be shown on a range of documents. The purpose of the ACN is to ensure adequate identification of companies when transacting business. New companies are issued with numbers by the Australian Securities & Investments Commission (ASIC) upon registration.
The ACN is generated using an algorithm with the last digit being a check digit allowing the number to be verified.
A company's ACN should appear on all of its 'public documents' and 'eligible negotiable instruments' (s153). The items on which it should appear include:
all documents required to be lodged with ASIC
statements of account, including invoices
receipts (which are not machine-produced)
orders for goods and services
official company notices
cheques, promissory notes and bills of exchange, and
written advertisements making a specific offer which is capable of being accepted (such as by the completion of an order form).
If a company's name appears on two or more pages of a document or instrument, the ACN must be shown on the first of those pages following the company's name.
Where a number of separate companies are listed on a document (eg, a letterhead) the ACN of each should appear and in such a way that makes clear the company to which each ACN relates.
While there are no specific requirements as to how an ACN should appear on a document, it should be clear, easily readable, and obvious as to the company to which it relates.
The ACN should be identified by the words 'Australian Company Number', or by the abbreviations 'ACN' or 'A.C.N.'.
Australian Business Number
If your company has an Australian Business Number (ABN), you may use the ABN with your company's name in place of the ACN on company documents and negotiable instruments, provided that:
your ABN includes your nine digit ACN, and
the quotation of the ABN is effected in the same manner in which quotation of the ACN would normally occur. (For example, a company is required to place its ACN with its name on the first page where that name appears in a document).
For further information about the legal requirements in relation to Australian Business Numbers, contact the Australian Taxation Office.
A company may have a common seal (s123), and then use it to execute documents in accordance with its constitution. It is not compulsory for a company to have a common seal. If a company does have a common seal, it must set out the following information:
for a company that has its Australian Company Number (ACN) as its name - the company’s ACN, or
the company’s name, the expression 'Australian Company Number' and the company’s ACN. or
if the last 9 digits of the company's ABN are the same, and in the same order, as the last 9 digits of its ACN - the expression "Australian Business Number" and the company's ABN.
ACN or A.C.N. are acceptable abbreviations for Australian Company Number. A company may make contracts and execute documents without using a seal (see s126 and s127).
Where the ACN is not required
The items on which the ACN is not required include:
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 (eg, vehicles, television advertisements).
The penalty for non-compliance with the ACN provision of the Corporations Act 2001 (s153) is $1,700 or three months imprisonment, or both.
More company information
For a contents list of more information about companies and their administration, see our For companies page. For further information about the legal requirements in relation to Australian Company Numbers, see ASIC's Regulatory Guide 13ACN, ARBN and company names.
This is Information Sheet 13 (INFO 13). Information sheets provide concise guidance on a specific process or compliance issue or an overview of detailed guidance.