The difference between an ABN and an ACN comes down to who issues the number and why. An ABN (Australian Business Number) is an 11-digit number from the Australian Taxation Office that identifies your business for tax. An ACN (Australian Company Number) is a 9-digit number from ASIC that only exists once you register a company. Every business needs an ABN. Only companies get an ACN.
If you have ever stared at a registration form wondering which number you actually need, you are in good company. Most people setting up a business mix these two up. And the confusion usually is not about the numbers at all. It is about whether you should be a sole trader or a company, which is the real question sitting underneath.
- ABN is for every business, ACN is for companies only. A sole trader has an ABN and no ACN. A company has both.
- Different issuers. The ATO issues your ABN. ASIC issues your ACN.
- For a company, the ACN comes first. You register the company, ASIC issues the ACN, then the company gets an ABN built from that ACN.
- An ABN is free. An ACN is not. Registering a company costs $611 with ASIC for 2025-26, plus a $329 annual review each year.
- No ABN on the invoice means a 47% hit. If you do not quote an ABN, other businesses must withhold 47% of what they pay you and send it to the ATO.
Table of Contents
What’s the difference between an ABN and an ACN?
Your ABN identifies your business to the ATO, the government and the people you trade with. An ACN identifies your company as a separate legal entity registered with ASIC. Put simply, the ABN is about tax and the ACN is about company status.
Here is the part most explainers skip: for a company, the two numbers are linked. Your 11-digit ABN is built from your 9-digit ACN, with two extra digits on the front. So a company does not really choose between them. It has an ACN because it is a company, and an ABN because it trades.
| Feature | ABN (Australian Business Number) | ACN (Australian Company Number) |
|---|---|---|
| What it is | A tax and identification number for any business | A registration number for a company |
| Issued by | Australian Taxation Office (via the Australian Business Register) | Australian Securities and Investments Commission (ASIC) |
| Digits | 11 | 9 |
| Who needs it | Every business: sole traders, partnerships, trusts and companies | Companies only (for example a Pty Ltd) |
| Main purpose | Tax, GST, invoicing, dealing with government | Identifying the company as a separate legal entity |
| Cost (2025-26) | Free | $611 to register the company, then $329 a year |
| Where it appears | Invoices, quotes, business documents, ABN Lookup | Company documents, public notices, the ASIC register |
What is an ABN (Australian Business Number)?
An ABN is a unique 11-digit number that identifies your business. The ATO uses it to track your business activity and tax. You quote it on invoices, you need it to register for GST, and other businesses use it to check you are a real, registered operation.
Who needs an ABN?
Any business carrying on an enterprise in Australia can hold an ABN: sole traders, partnerships, trusts and companies. Here is the myth worth killing early. Trading without an ABN is not illegal for everyone. It is not compulsory until your turnover hits the $75,000 GST threshold, at which point you need an ABN to register for GST.
There are two big reasons to get one anyway. Without an ABN quoted on your invoice, the business paying you must withhold 47% under no-ABN withholding rules and send it to the ATO. And one exception trips people up constantly: rideshare and taxi drivers must register for GST, and so hold an ABN, from their very first dollar.
What you use an ABN for
- Putting a valid tax invoice in front of clients
- Registering for GST once you reach the threshold
- Dealing with the ATO on tax, PAYG and BAS
- Registering a business name to trade under
- Claiming GST credits on business purchases
- Securing a .au domain name for your website
Applying is free and takes about 15 minutes through the Australian Business Register. Sole traders should have their Tax File Number ready. If you want to skip the government portals, you can register your ABN through Lawpath in the same flow as your other setup tasks.
Start your ABN application in minutes!
What is an ACN (Australian Company Number)?
An ACN is a unique 9-digit number issued by ASIC the moment you register a company. It is how ASIC tracks your company and how the public confirms your company exists and who runs it. You will see it referenced under the Corporations Act 2001 (Cth), the law your company now answers to.
Who needs an ACN?
Only companies. If you register a proprietary limited company (Pty Ltd), ASIC issues your ACN at registration. Sole traders, partnerships and trusts never get one, because they are not companies. The one wrinkle: a trust with a company acting as its trustee will have an ACN for that trustee company.
What an ACN is for
The ACN marks your company as a separate legal entity. That separation is the whole point of being a company. The business owns its debts and obligations, not you personally, which is what shields your house and savings if things go wrong. The ACN is the public marker of that status, and it must appear on key company documents.
One thing the ACN does not do is replace your ABN. A company still needs an ABN to trade, invoice and handle tax. So a trading company carries both numbers, doing two different jobs.
Do you need an ABN, an ACN, or both?
Your business structure decides it for you. This is the question people are really asking when they search ABN vs ACN, so here it is in plain terms.
- Sole trader: ABN only. You invoice and deal with the ATO under your ABN. No ACN, because you are not a company.
- Partnership or trust: ABN only, unless a company acts as the trustee, in which case that company has an ACN.
- Company (Pty Ltd): both. You get an ACN when ASIC registers the company, and the company applies for its own ABN to trade.
If you are weighing up which structure fits, that is a bigger decision than the numbers, and it is worth getting right the first time. Our guide on sole trader vs company structure walks through the trade-offs.
How do you apply for an ABN and an ACN?
The order matters, and it is the opposite of what many people assume. You do not apply for an ACN on its own. You register a company, and the ACN comes with it. Then the company gets its ABN.
Getting an ABN
- Confirm you are carrying on an enterprise (running or genuinely starting a business).
- Gather your details: legal name, any business name, address, and your Tax File Number.
- Apply free through the Australian Business Register, or through a provider that does it alongside your other registrations. It takes about 15 minutes.
Getting an ACN
- Choose a company name and check it is available.
- Register the company with ASIC. The fee is $611 for 2025-26. ASIC issues your ACN on registration.
- Apply for the company’s ABN, which is built from the new ACN. Then register for GST if you expect to cross $75,000.
Budget for the ongoing cost, not just the setup. A company pays a $329 ASIC annual review fee every year, indexed each 1 July. You can register a company and pick up the ACN, ABN and tax registrations together, rather than chasing three separate government bodies.
What we see in Lawpath consultations
Across Lawpath advisor consultations, the ABN vs ACN question rarely turns up on its own. Three patterns come up again and again, and they are the things a search result usually misses.
The number question is really a structure question. When someone asks our advisors whether they need an ACN, what they are usually asking is whether they should become a company. Our lawyers see it most often the moment a sole trader starts taking on subcontractors or chasing larger contracts, because that is when personal liability stops being theoretical. The ACN is just the visible sign of the structure change that actually protects them.
The $75,000 GST myth runs deep. A lot of new founders believe they must register for GST, and have the full setup, from day one. Our advisors regularly reset that: under $75,000 turnover, GST registration is optional for most businesses, and there is no rush to over-build. The exception, rideshare and taxi work, catches part-time drivers off guard every time.
Moving from sole trader to company trips people up. A common assumption is that your ABN simply carries across when you incorporate. It does not. The company gets a brand new ABN built from its ACN, and you cancel the old sole trader ABN once you have stopped trading that way. Cancel it too early, before the company ABN is live, and you can be left unable to invoice for a window. We cover the timing in our guide on whether you need a new ABN when you incorporate.
Where do you display your ABN and ACN?
You do not need to plaster both numbers on every document. The rules are simpler than the long checklists suggest.
- A sole trader or partnership shows their ABN on tax invoices and business documents.
- A company must show its ACN (or its ABN, since the ABN already contains the ACN) on public documents such as invoices, letterhead, official notices and anything lodged with ASIC.
So in practice, a company can put its ABN on most documents and still meet the ACN display rule, because the ACN is embedded inside it. Leave the numbers off where they are required and you risk penalties from the ATO or ASIC, so it is worth getting your invoice template right once.
Frequently asked questions
Is an ABN and ACN the same thing?
No. An ABN is your tax identifier issued by the ATO, and every business has one. An ACN is issued by ASIC and only exists if you have registered a company. They look similar and often sit on the same documents, but they do different jobs.
Can you have an ACN without an ABN?
Technically yes, but it is rare. A company is issued its ACN the moment ASIC registers it, even before it gets an ABN. In practice almost every trading company applies for an ABN straight away, because it cannot invoice or register for GST without one.
Can you have an ABN without an ACN?
Yes, and most businesses do. Every sole trader, partnership and trust runs on an ABN with no ACN, because they are not companies. You only pick up an ACN if you register a company with ASIC.
Does my ABN change if I become a company?
Yes. You cannot move a sole trader ABN across to a company. The company gets its own new ABN, built from its ACN, and you cancel your old sole trader ABN once you have genuinely stopped trading as a sole trader.
How much does an ABN or ACN cost?
Applying for an ABN is free through the Australian Business Register. An ACN comes with registering a company, which costs $611 with ASIC for 2025-26, plus a $329 annual review fee each year after that. ASIC fees rise with CPI every 1 July.
Do I legally need an ABN to run a business in Australia?
Not always. An ABN is not compulsory under $75,000 turnover, but without one others must withhold 47% of payments to you, and you need an ABN before you can register for GST. Rideshare and taxi drivers must register for GST, and so hold an ABN, from their first dollar.
How many digits are an ABN and an ACN?
Your ABN is 11 digits and your ACN is 9 digits. For a company, the two are linked: your 11-digit ABN is built from your 9-digit ACN with two extra digits at the front.
Which number goes on my invoices?
Put your ABN on invoices. A sole trader uses their ABN, and a company can show its ABN too, because it already contains the ACN. A company that does not quote its ABN must show its ACN on the invoice instead.
If this still feels like alphabet soup, that is completely normal. Almost everyone setting up a business hits the same wall, and sorting it out early is far easier than untangling it after you have been trading for a year. You are not behind. You are doing the part most people put off.
Ready to set it up properly? Register your company with Lawpath and get your ACN, ABN and tax registrations sorted in one place, without bouncing between ASIC, the ABR and the ATO.
