- An ABN is a free, 11-digit number from the ABR that shows you're running a genuine enterprise, not a hobby.
- You generally need an ABN once you invoice for goods or services, or clients may withhold tax from what they pay you.
- An ABN is different from an ACN (a company number from ASIC) and a TFN (your personal tax number from the ATO).
What is an ABN? It’s an 11-digit number that identifies your business to the ATO and to the businesses you deal with. The Australian Business Register (ABR) issues it free of charge once you can show you’re carrying on a genuine enterprise, not just a hobby.
Sole traders, partnerships, companies and trusts can all hold one, and it’s separate from a tax file number or a company number. Skip it, and clients may need to withhold tax from what they pay you, and you can’t register for GST.
What is an ABN?
An ABN, short for Australian Business Number, is the 11-digit identifier the ABR gives your business or enterprise. It’s how the ATO, other businesses and government agencies recognise you when you trade, invoice or deal with them. You’ll use it on invoices, when registering for GST, and when dealing with suppliers and clients.
Not everyone is entitled to one. The ABR only issues an ABN to entities carrying on an enterprise, which includes running a business, acting as a trustee, operating a charity, or leasing property. A one-off hobby sale or a single side gig with no ongoing intention to profit generally doesn’t qualify.
Applying for an ABN itself is free through the ABR’s online portal. There’s no cost to hold one, though you may pay a registered agent or accountant to help you apply and set up related registrations correctly.
Do you need an ABN?
You generally need an ABN if you’re running any kind of enterprise, even a small one on the side. Here’s a quick way to check.
You likely need an ABN if you:
- Invoice clients for goods or services, even occasionally.
- Plan to register for GST or claim GST credits.
- Are setting up as a sole trader, partnership, company or trust that trades.
- Act as a trustee for a super fund, including an SMSF.
You probably don’t need one yet if you:
- Are an employee, including a casual or apprentice, paid through PAYG.
- Are making a single, occasional private sale with no ongoing business intention.
- Rent out a residential property with no other enterprise activity.
If you sell to a business without quoting an ABN, that business may have to withhold tax from your payment once the amount passes $75, excluding GST. That’s one reason it’s worth choosing to register your ABN with Sleek before you send your first invoice, rather than after a client asks for one. You can read more about why no ABN means top-rate withholding if you want the full mechanics.
Running a side hustle alongside a regular job is one of the most common triggers for needing an ABN. If that’s you, it’s worth checking the rules around an ABN for a side hustle before you invoice anyone.
ABN vs ACN vs TFN: what’s the difference?
An ABN identifies your business, an ACN identifies a registered company, and a TFN identifies you personally for income tax. They’re issued by different bodies, for different reasons, and you can hold more than one at once.
Your ACN comes from ASIC the moment you register a company, and it’s always nine digits. Your ABN, if the company also has one, is often the same nine digits with two extra numbers added to the front, making 11 digits in total. A TFN, by contrast, belongs to you as an individual (or to your company or trust separately) and is used for lodging tax returns, not for identifying you to trading partners.
| Feature | ABN | ACN | TFN |
|---|---|---|---|
| Issued by | Australian Business Register (ABR) | ASIC | ATO |
| Format | 11 digits | 9 digits | 9 digits |
| Who has one | Sole traders, partnerships, companies and trusts running an enterprise | Registered companies only | Individuals, and companies or trusts, for income tax purposes |
| Cost to obtain | Free | Fee applies, paid to ASIC | Free |
| Main purpose | Identifies your business to the ATO and other businesses | Identifies a company as a legal entity | Identifies you for personal or entity income tax |
TIPIf you’re planning to register a company, you’ll get both an ACN and an ABN at once, so you don’t need to apply for them separately.
How do you get an ABN?
You apply for an ABN online through the ABR, and most straightforward applications are approved instantly. You’ll need to answer questions that help the ABR confirm you’re genuinely carrying on an enterprise, not just testing an idea.
Before you start, have these ready: your tax file number, your business structure (sole trader, partnership, company or trust), your business address, and a description of your main activity. Providing your TFN speeds up processing, since it helps the ABR verify your identity.
If your application needs extra checking, you’ll get a reference number instead of an instant ABN. The ABR aims to review these within 20 business days and will contact you if it needs more information. Once approved, you can immediately apply for other registrations like GST.
If your enterprise hasn’t started trading yet, you’ll still need to show some commencement activity, such as setting up a website, buying stock, or issuing quotes for work.
What’s different about ABNs for sole traders, companies and trusts?
The ABN itself works the same way no matter your structure, but who applies for it, and what else comes with it, changes. A sole trader applies in their own name and uses their personal TFN. A company applies as a separate legal entity and typically gets an ACN at the same time.
Sole traders are the simplest case. You use your own TFN, the ABN sits under your name, and you’re personally liable for the business.
Companies are different because registering a company with ASIC gives you a separate legal entity, an ACN, and usually an ABN derived from it. The company, not you personally, holds the ABN and is liable for its debts.
Trusts need an ABN in the name of the trustee, who applies on the trust’s behalf. This matters for self-managed super funds too. If you’re setting one up, the ABN rules work a little differently, and it’s worth reading about ABNs for an SMSF before you apply.
What can you do with an ABN?
Having an ABN lets you invoice clients without tax being withheld, register for GST, and claim GST credits on business purchases. It also lets you apply for a business name, order supplies at trade prices, and appear in the ABN Lookup register that clients often check before paying you.
Without one, a business paying you more than $75 generally has to withhold tax at the top rate and send it to the ATO instead of paying you in full. Many suppliers avoid this by lodging a statement instead of quoting an ABN. If that sounds like your situation, it’s worth understanding what working without an ABN actually involves before you decide.
Sole traders in particular often pair an ABN with proper bookkeeping from day one. Getting your sole trader tax and accounting sorted alongside your ABN means you’re not scrambling at tax time.
How Sleek helps you register your ABN
Sleek registers your ABN as part of getting your business set up properly, alongside GST, PAYG and TFN registration where you need them. If you’re forming a company at the same time, Sleek handles the ACN and ABN together so you’re not juggling two separate applications.
For sole traders, Sleek can also take care of your ongoing tax and accounting once your ABN is active, so the paperwork doesn’t pile up later.
Ready to get your ABN sorted?
Get your ABN sorted and talk to an expert. Sleek’s Company Registration Launch plan lists at A$300 a year plus ASIC fees, and includes ABN, GST, PAYG and TFN registration.
Prices may vary with current promotions, check the latest on the relevant page.
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Frequently Asked Questions
Is an ABN the same as a business name?
No. An ABN identifies your enterprise for tax and trading purposes, while a business name is the trading name you operate under if it’s different from your own or your company’s legal name. You can hold an ABN without registering a separate business name if you trade under your own legal name.
Can I have more than one ABN?
No, each entity gets one ABN. If you’re a sole trader running two different activities, both usually sit under the same ABN, though you may need separate business names for each.
How long does it take to get an ABN?
Most straightforward applications are approved instantly online. If the ABR needs to check your details, it aims to complete that review within 20 business days.
Is an ABN free to apply for?
Yes, applying through the ABR’s online portal costs nothing. You only pay if you use a registered agent, accountant or service like Sleek to prepare and lodge the application for you.
What happens if I don't have an ABN?
Businesses paying you more than $75 for goods or services generally must withhold tax at the top rate and remit it to the ATO, rather than paying you the full amount. You also can’t register for GST or claim GST credits without one.
Do I need an ABN for a side hustle or hobby?
Once your side activity is repeated, systematic and run with an intention to profit, it’s likely an enterprise and needs an ABN. A genuine one-off hobby sale with no ongoing commercial intent usually doesn’t qualify.
Can I cancel my ABN?
Yes, you can cancel your ABN through the ABR if you stop trading or close your business. You should also cancel related registrations like GST at the same time to avoid ongoing lodgement obligations.
