Reading time: 6 minutes

An ‘Australian Company Number’ (ACN) is a unique 9-digit number issued by the Australian Securities and Investments Commission (ASIC). You will receive an ACN to identify your company when you incorporate it. This article will explain the purpose of an ACN and outline key documents that the Corporations Act and regulations require your ACN and your company name to appear on.

What is An ACN?

If your company name ends in ‘Pty Ltd’ or ‘Proprietary Limited’, ‘Ltd’ or ‘Limited’, this indicates that you have registered a company. Likewise, you would have been issued an ACN upon registration. An ACN is different to an ABN (‘Australian Business Number’), as an ABN can be issued to anyone carrying out business activities, such as a sole trader. Indeed, an ACN is purely for companies.

Including your ACN and company name on certain documentation is important, as it allows other businesses and people to identify you. As many companies have similar names and subsidiaries, ACNs help to reduce fraud. Indeed, they make it possible to identify your particular company clearly.

If you decide to change your company name, you can keep the same ACN.

Which Documents Must Display My ACN?

Generally, your company’s ACN should appear on all of your:

  • ‘public documents’ (i.e. documents that are available for public use or reference); and
  • ‘eligible negotiable instruments’ (i.e. documents that promise a certain payment, such as a contract or order for service).

Your company name and ACN should appear next to each other on the first page of the document. You can display your ACN in several ways, so long as you write and display this clearly, it is easily readable, and it is obvious as to which Company it belongs. This particularly applies when you list multiple companies on a document – you must clearly display the ACN for each corresponding company.

Likewise, you may write:

  •     ‘Australian Company Number’;
  •     ‘ACN’; or
  •     ‘A.C.N.’.

For example, you could list Beds and Tables Pty Ltd ACN 123 456 789 at the top of the document.

If your company has an ABN, then you can use this number instead of the ACN provided that:

  •     the last 9 digits of your ABN are the same as your ACN; and
  •     you present the ABN in the same way that you are required to present your ACN.

Using the above example, this would read as Beds and Tables Pty Ltd ABN 12 123 456 789.

Below are some examples of common documents that require your ACN and company name.

Any Documents You Lodge With ASIC

You must include your ACN and company name on any documents that you lodge with ASIC, including: 

  •     share transfer forms;
  •     company name change forms; and
  •     forms to change the director of a company.

Invoices and Statements of Accounts

When you issue invoices, your clients need to ensure that they pay the correct company. Including your ACN allows clients to identify your company with greater certainty and reduces the likelihood of a costly mistake.

Handwritten Receipts

A handwritten receipt (or acknowledging of payment) must contain your ACN so that the purchaser knows who they have purchased the product or service from.

Order Forms for Goods and Services

Similarly, if you are ordering goods or services for your business, the supplier should be able to identify to who they are providing their goods or services. The added certainty of identification also assists should you want to pursue a claim against the supplier for any reason. 

Business Letterheads and Other Official Documentation

Business letterheads are considered public documents and therefore must contain your ACN. Although there is no legal requirement to contain other information, many businesses will voluntarily include details such as the business’:

  •     operating address;
  •     contact email address; and
  •     phone number.

This allows their clients and service providers to contact them more easily.

Official Company Notices

This includes tax returns and any disclosure notices, such as when supplier companies issue public notices about defective goods.

Cheques, Promissory Notes and Bills of Exchange

Any company that enters into a transaction should be easily identifiable.

Written Advertisements

When you publish written advertisements, beware of any legal requirements you must comply with if it falls within the definition of a ‘public document’.  

For example, in respect of an ‘official company notice’, as a general rule, an advertisement is not an official notice unless you must publish it according to:

  •     your company’s constituent documents (i.e. your company constitution); or
  •     under statute or for government purposes.

For example, under Australian corporations law, you must provide notice when advertising a proposed share buy-back.

Use of Common Seals

Whilst less common today, a company may opt to use a common seal to execute public documents. Generally, a company’s constitution will establish the process requiring the use of a seal. However, it is not compulsory to use one. 

Companies that elect to use a common seal must include:

  • the company’s name, the expression ‘Australian Company Number’ and the company’s ACN, or
  • if the company uses its ABN instead of the ACN, the company’s name, the expression ‘Australian Business Number’ and the company’s ABN.

Which Documents Do Not Require My ACN?

Not all documents will require your ACN, and there are specific exemptions at law. For example, you do not need to print your ACN on:

  •     machine, cash-register or software generated receipts;
  •     advertisements that promote the company without making a specific offer;
  •     credit cards or vouchers;
  •     materials that are not documents (e.g. signs or television advertisements);
  •     packaging and labelling (including envelopes and transport documents); or
  •     business cards or ‘with compliments’ slips.


If you fail to have an ACN appear on required documents, financial penalties of $1,100 per offence could apply.

Directors' Duties Complete Guide

If you are a company director, complying with directors’ duties are core to adhering to corporate governance laws.
This guide will help you understand the directors’ duties that apply to you within the Australian corporate law framework.

Download Now

Key Takeaways

Your ACN is an important identifier for your company. You must include your ACN or ABN wherever necessary so that other businesses and the public know who they are engaging for a business relationship. You may also face harsh penalties if you do not display your company name and ACN where you are required. As a general rule, you should include your company name and ACN on any public documents or negotiable instruments. 

If you need help understanding your corporate obligations or assistance registering your company, our experienced business lawyers can assist as part of our LegalVision membership. For a low monthly fee, you will have unlimited access to lawyers to answer your questions and draft and review your documents. Call us today on 1300 544 755 or visit our membership page.

Frequently Asked Questions

What is an Australian Company Number?

An ‘Australian Company Number’ (ACN) is a unique 9-digit number issued by the Australian Securities and Investments Commission (ASIC). You will receive an ACN to identify your company when you incorporate it. 

Which documents should my ACN appear on?

You should include your ACN on any documents you lodge with ASIC, invoices and statements of accounts, handwritten receipts, order forms for goods and services, and business letterheads, amongst other official documents.


Redundancies and Restructuring: Understanding Your Employer Obligations

Thursday 7 July | 11:00 - 11:45am

If you plan on making a role redundant, it is crucial that you understand your employer obligations. Our free webinar will explain.
Register Now

How to Sponsor Foreign Workers For Your Tech Business

Wednesday 13 July | 11:00 - 11:45am

Need web3 talent for your tech business? Consider sponsoring workers from overseas. Join our free webinar to learn more.
Register Now

Advertising 101: Social Media, Influencers and the Law

Thursday 21 July | 11:00 - 11:45am

Learn how to promote your business on social media without breaking the law. Register for our free webinar today.
Register Now

Structuring for Certainty in Uncertain Times

Tuesday 26 July | 12:00 - 12:45pm

Learn how to structure to weather storm and ensure you can take advantage of the “green shoots” opportunities arising on the other side of a recession.
Register Now

Playing for the Prize: How to Run Trade Promotions

Thursday 28 July | 11:00 - 11:45am

Running a promotion with a prize? Your business has specific trade promotion obligations. Join our free webinar to learn more.
Register Now

Web3 Essentials: Understanding SAFT Agreements

Tuesday 2 August | 11:00 - 11:45am

Learn how SAFT Agreements can help your Web3 business when raising capital. Register today for our free webinar.
Register Now

Understanding Your Annual Franchise Update Obligations

Wednesday 3 August | 11:00 - 11:45am

Franchisors must meet annual reporting obligations each October. Understand your legal requirements by registering for our free webinar today.
Register Now

Legal Essentials for Product Manufacturers

Thursday 11 August | 11:00 - 11:45am

As a product manufacturer, do you know your legal obligations if there is a product recall? Join our free webinar to learn more.
Register Now

About LegalVision: LegalVision is a commercial law firm that provides businesses with affordable and ongoing legal assistance through our industry-first membership.

By becoming a member, you'll have an experienced legal team ready to answer your questions, draft and review your contracts, and resolve your disputes. All the legal assistance your business needs, for a low monthly fee.

Learn more about our membership

Need Legal Help? Submit an Enquiry

If you would like to get in touch with our team and learn more about how our membership can help your business, fill out the form below.

Our Awards

  • 2020 Innovation Award 2020 Excellence in Technology & Innovation Finalist – Australasian Law Awards
  • 2020 Employer of Choice Award 2020 Employer of Choice Winner – Australasian Lawyer
  • 2020 Financial Times Award 2021 Fastest Growing Law Firm - Financial Times APAC 500
  • 2020 AFR Fast 100 List - Australian Financial Review
  • 2021 Law Firm of the Year Award 2021 Law Firm of the Year - Australasian Law Awards
  • 2022 Law Firm of the Year Winner 2022 Law Firm of the Year - Australasian Law Awards