A company seal is a rubber stamp with the company’s name and Australian Company Number or ACN. It is the same thing as a common seal or a corporate seal.

Prior to 1988, company seals were mandatory for the execution of documents and it was compulsory that a seal was affixed to deeds. The Company Law Review Act 1988 abolished both requirements.

Regardless of the law, many companies today still choose to use a company seal. For instance, a company seal may give more legitimacy to documents for people unfamiliar with the Australian way of document execution. If a company has many overseas clients, this may be a way to show legality and validity.

Company Seal Requirements

If a company chooses to use a seal, in order for it to be valid it must include:

• For a company that has its Australian Company Number (ACN) as its name – the company’s ACN; or otherwise:
• 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 both acceptable abbreviations for Australian Company Number.
ABN or A.B.N are both acceptable abbreviation for Australian Business Number.