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Learn MoreHow to Register for an ABN in Australia:
2025 Step-by-Step Guide
An Australian Business Number (ABN) is the first thing you need before you can invoice clients, register for GST, or operate as a legitimate sole trader or small business. The good news. It's free, takes 15 minutes, and you can do it right now.
Written by Rob, founder of AusCalc
Australian small business owner. Checked against current ATO published rates. Updated July 2026. About AusCalc
What is an ABN?
An Australian Business Number (ABN) is a unique 11-digit identifier issued by the Australian Business Register (ABR). It identifies your business to the government, the ATO, and other businesses.
You need an ABN to legitimately invoice clients, register for GST, claim GST credits, and avoid having other businesses withhold the top rate of tax from payments they make to you.
Do You Need an ABN?
You should register for an ABN if you are carrying on a business enterprise in Australia. This includes freelancers, contractors, sole traders, partnerships, and companies.
If you invoice another business without providing an ABN, they are legally required to withhold 47% of the payment and send it to the ATO. It is essential to get your ABN before sending your first invoice.
You do not need an ABN if you are working purely as an employee with no separate business activity.
How to Apply for an ABN
Go to abr.gov.au
Visit the official ABR website. Registration is free; ignore third-party sites charging fees.
Select Structure
Choose your business structure (e.g., Sole Trader or Company).
Enter Details
Provide your TFN, date of birth, address, and personal identification.
Describe Activity
Select your main business activity and industry (ANZSIC code).
Submit Application
Most applications are approved instantly. Complex cases may take 28 days.
Ready to Use
Save your 11-digit ABN and add it to your invoices immediately.
ABN for Sole Traders vs Companies
Sole traders use their ABN for all business activity. The ABN is tied to you personally, so if you change your trading name, your ABN stays the same.
In contrast, a company must first register with ASIC to get an Australian Company Number (ACN). The company then uses its ACN to apply for its own unique ABN. Sole trader applications are generally faster and simpler to manage.
Business Name Registration
Getting an ABN does not automatically register a business name. If you want to trade under any name other than your own legal name, you must register the name with ASIC.
For example, Jane Smith doesn't need a business name to trade as "Jane Smith". However, if she wants to trade as "Jane's Design Studio", she must register that name through ASIC Connect (costs approx $44 for 1 year or $102 for 3 years).
Visit ASIC ConnectWhat an ABN Actually Changes About Your Tax
Getting an ABN does not create a new tax account or a new tax rate. You still pay tax at individual rates on your profit through your personal return. What changes is the collection mechanics: nothing is withheld from your invoices, so budgeting for tax becomes your job from the very first dollar. Our sole trader tax calculator shows what to set aside.
There is one withholding rule every new ABN holder should know from the other side of the invoice. If a supplier does not quote an ABN on an invoice over $75, the paying business is generally required to withhold 47 percent of the payment (the no-ABN withholding rule). This is why clients chase you for your ABN before paying, and why it goes on every invoice you send.
Also worth understanding is the hobby line. An ABN is for activity carried on as a business, with intention to profit, repetition, and organisation. Selling the occasional item or doing a one-off favour for payment can legitimately be a hobby, which means no ABN and no tax, but also no deductions. If your activity is regular and aimed at profit, the ATO view is that it is a business regardless of what you call it.
Keeping Your ABN Active and Accurate
The Australian Business Register periodically cancels ABNs that look inactive, typically because no business income has been reported for a couple of years. If that happens to you mid-contract it can hold up payment, because clients validate your ABN through ABN Lookup before paying invoices. Reapplying is quick and usually restores the same number, but it is disruption you can avoid by keeping lodgements up to date.
You are also legally required to update your ABR details within 28 days of a change, including your business address, contact details, and main business activity. It takes five minutes through your myGov linked ABR access and keeps your public ABN Lookup record accurate, which clients and platforms increasingly check automatically.
One quiet benefit of an accurate ABR record: banks and lenders use your ABN registration date as evidence of how long you have been trading, which matters when a sole trader applies for finance. The earlier your record is right, the cleaner that history looks.
After Your ABN. What's Next?
Once you have your ABN, you have completed the first step of your business journey. Next, you should:
Register for GST: If your turnover will exceed $75,000. Read the GST Guide.
Understand Your Taxes: Factor in PAYG and sole trader tax obligations. Read the Sole Trader Guide.
Open a Bank Account: Keep your business and personal expenses strictly separate from day one.
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Standard ATO estimates only; consult a professional before acting. For more details, see our Disclaimer.