If you run a business in Australia, you've probably wondered whether you need to include your Australian Business Number (ABN) in your email signature. The short answer: yes, in most cases you should. Here's a detailed breakdown of the legal requirements and best practices.
What the Law Says
Under the A New Tax System (Australian Business Number) Act 1999, businesses are required to display their ABN on business documents. While the Act specifically references invoices, purchase orders, and similar documents, the ATO's guidance is broader — business correspondence, including email, should include your ABN when dealing with other businesses.
Additionally, the Corporations Act 2001 (Section 153) requires registered companies to display their company name and ACN (Australian Company Number) on all public documents and negotiable instruments. ASIC considers business emails to fall under this requirement.
ABN vs ACN — What's the Difference?
ABN (Australian Business Number)
An 11-digit number identifying a business entity. Required for GST registration, invoicing, and government dealings. All businesses (sole traders, partnerships, companies, trusts) can have an ABN.
ACN (Australian Company Number)
A 9-digit number assigned to companies registered with ASIC. Only Pty Ltd and Ltd companies have an ACN. Legally required to be displayed on all public documents — including emails.
If you're a registered company (Pty Ltd): You should display both your ABN and ACN.
If you're a sole trader or partnership: Include your ABN. You won't have an ACN.
What Else Should Australian Businesses Include?
Beyond the ABN/ACN, several industries have their own email signature requirements:
- Real Estate Agents — Must display their real estate licence number and agency details. Requirements vary by state (NSW Fair Trading, Consumer Affairs Victoria, etc.).
- Financial Services — AFSL (Australian Financial Services Licence) number must be displayed. General disclaimers about advice are also standard practice.
- Health Practitioners — AHPRA registration number. Under AHPRA guidelines, health practitioners must not make misleading claims.
- Lawyers — Practising certificate number. Many also include "Liability limited by a scheme approved under Professional Standards Legislation."
- Builders & Tradespeople — Builder's licence number and registration details, as required by state building authorities.
Do You Need a Confidentiality Disclaimer?
Confidentiality disclaimers (the "this email is intended for..." paragraph) are extremely common in Australian business emails, especially in legal, financial, and government sectors. But do you legally need one?
Strictly speaking, no — there is no Australian law requiring a confidentiality disclaimer on general business emails. However, they are considered standard practice in certain industries and can provide some legal protection if an email is misdirected. Most law firms and financial institutions include them as a matter of policy.
💡 Standard Australian confidentiality disclaimer:
"This email and any attachments are confidential and may be legally privileged. If you are not the intended recipient, please notify the sender immediately and delete all copies. Any unauthorised use, disclosure, distribution, or copying is strictly prohibited."
How to Include Your ABN Elegantly
There's no need for your ABN to be the first thing people see. Place it tastefully at the bottom of your signature in a smaller font. Here are some common formats:
ABN 12 345 678 901ABN 12 345 678 901 | ACN 123 456 789Company Pty Ltd | ABN 12 345 678 901
Our email signature templates have a dedicated field for your ABN — it's formatted and positioned professionally within the design. No manual HTML editing required.
Summary
- Sole traders: Include ABN — recommended on all business emails
- Companies (Pty Ltd): Include ACN (legally required) and ABN
- Licensed professionals: Include relevant licence/registration numbers
- Confidentiality disclaimer: Not legally required, but standard practice in legal/financial sectors
When in doubt, include it. Your ABN takes up one line of space but demonstrates professionalism and compliance. It's a small detail that gives clients and partners confidence in your legitimacy.
Disclaimer: This article provides general guidance only. It is not legal advice. For specific legal requirements regarding your business communications, consult a qualified legal professional.