An ABN is the 11-digit number every business in Australia needs to trade; an ACN is the 9-digit number that only registered companies have. Sole traders and partnerships need an ABN only. Companies get an ACN from ASIC when they incorporate, then apply for an ABN as well. The two numbers do different jobs.
Side by side
| ABN | ACN | |
|---|---|---|
| Stands for | Australian Business Number | Australian Company Number |
| Digits | 11 | 9 |
| Issued by | Australian Business Register (ATO) | ASIC |
| Who has one | Every trading entity: sole traders, partnerships, trusts, companies | Registered companies only |
| What it’s for | Invoicing, GST, dealing with the ATO and other businesses | The company’s legal existence and ASIC compliance |
| Cost | Free from the ABR ($99 agent-lodged with review) | ASIC registration fees + annual review fees |
The practical rule
Starting out on your own? You’re a sole trader: apply for an ABN and you’re in business, no ACN exists for you, and anyone who says you need one is confused. Incorporating a company? ASIC gives the company its ACN at registration, and the company then needs its own ABN too (a company can’t trade on the director’s personal ABN). And if you’ve been handed a number and want to know what it belongs to, our free ABN lookup reads the register live. Mixing up an ABN with your TFN is a different, more common confusion. See our ABN vs TFN guide if that's the one you're after.
Common questions
What’s the difference between an ABN and an ACN?
An ABN (Australian Business Number, 11 digits) identifies any entity doing business (sole traders, partnerships, trusts and companies) and is issued by the Australian Business Register. An ACN (Australian Company Number, 9 digits) is issued by ASIC and identifies registered companies only. A company has both; a sole trader has just an ABN.
Do sole traders need an ACN?
No. Sole traders aren’t companies, so there’s no ACN involved. You need an ABN only. If you later incorporate, the new company gets an ACN from ASIC and then applies for its own ABN.
Why does a company have both an ABN and an ACN?
The ACN creates the company (ASIC’s register); the ABN lets it do business (invoicing, GST, dealing with the ATO). A company’s ABN is usually its ACN with two leading digits added.
Should I start as a sole trader or a company?
Most people start as sole traders, cheaper, simpler, and profits taxed at personal rates. Companies add limited liability and different tax treatment at the cost of setup fees, annual ASIC fees and compliance. That’s a structure decision worth actual advice. Call 1800 546 526 and we’ll point you honestly, including when “just get a sole trader ABN” is the right answer.
How do I check an ABN or ACN?
Both are public. Look up any ABN or ACN free (entity name, status, GST registration) using our ABN lookup tool, which reads live from the Australian Business Register.
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