ABN vs ACN in Australia: what's the difference?
If you're comparing ABN vs ACN while planning a company registration or ABN application, you're looking at two different identifiers issued by two different agencies. They often appear together, but they solve separate tax and legal requirements.
What is an ABN?
An Australian Business Number (ABN) is an 11-digit number that identifies your business to the government and the public.
You'll need an ABN if you:
- Run a business (as a sole trader, partnership, company, or trust)
- Want to invoice customers and get paid properly
- Need to register for GST
- Want to claim business tax deductions
Your ABN is used across many government systems, including the Australian Taxation Office, and is typically displayed on invoices and business documents.
Think of an ABN as your business identity for tax and commercial purposes.
What is an ACN?
An Australian Company Number (ACN) is a 9-digit number issued to companies when they are registered with the Australian Securities and Investments Commission (ASIC).
An ACN is only required if you are running a company — not a sole trader or partnership.
You'll use your ACN:
- On official company documents
- When dealing with ASIC
- To legally identify your company on business letters, invoices, and websites
Think of an ACN as your company's legal identifier — issued at the moment of incorporation.
Key differences at a glance
| Feature | ABN | ACN |
|---|---|---|
| Number length | 11 digits | 9 digits |
| Who needs it | All business types | Companies only |
| Issued by | Australian Taxation Office | ASIC |
| Purpose | Tax & business identification | Legal company identification |
Do you need both?
Sometimes — yes.
If you register a Pty Ltd company, you will:
- Receive an ACN from ASIC when the company is incorporated
- Then apply for an ABN (your ABN will usually incorporate your ACN within it)
If you're a sole trader, you typically only need an ABN — not an ACN.
Quick examples
- Freelancer / sole trader → ABN only
- Partnership → ABN only
- Company (Pty Ltd) → Both ABN and ACN
How our platform handles this
When you register a Pty Ltd company through our platform, we submit your application to ASIC for an ACN. Registering for an ABN is part of your post-registration compliance roadmap, which guides you through the critical first steps — including your ABN application — within the first 7 days.
Final takeaway
- ABN = Business identity (for tax and trading)
- ACN = Company identity (for legal purposes)
Understanding the difference helps you register correctly and avoid delays when setting up your business.
About this guide
This guide is published by RSB Registrations, headquartered in Victoria, Australia, and reviewed by a Registered ASIC Agent alongside our technical lead to keep it aligned with current ASIC and ATO workflows.
We update these resources when core registration and compliance requirements change. Learn more about our team.
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