How to Register an ABN in Australia: Step-by-Step Guide

An Australian Business Number (ABN) is an 11-digit identifier that businesses use when dealing with the government and other businesses. If you are starting a business, working as a contractor, or earning income from a business activity in Australia, you will almost certainly need one. The good news is that registering for an ABN is free and can be done entirely online in about 15 minutes.

Who Needs an ABN?

You need an ABN if you are carrying on an enterprise in Australia. This includes:

Sole traders and contractors — if you provide services or sell goods as a business activity, not as an employee
Freelancers — designers, writers, developers, consultants, and other self-employed workers earning business income
Companies and partnerships — all registered companies and business partnerships must have an ABN
Tradies and tradespeople — anyone operating independently in a trade

You do not need an ABN if you are simply an employee receiving a salary or wages. If a client asks you for an ABN and you don't have one, they are legally required to withhold 47% of your payment under the no-ABN withholding rules — a strong incentive to get registered.

What You Need Before Applying

Before you start your application, gather the following:

Tax File Number (TFN) — your personal TFN links your ABN to the tax system
Personal details — full name, date of birth, and residential address
Business activity description — a brief description of the main business activity (e.g., "IT consulting", "graphic design", "carpentry services")
Business address — where your business will primarily operate from
Proof of enterprise — you need to be able to demonstrate that you are carrying on or about to start a business activity (not just seeking employment)

If you are registering on behalf of a company, trust, or partnership, you will also need the relevant legal documents such as an ACN (for a company) or trust deed details.

How to Register (Step by Step)

Go to abr.business.gov.au — this is the Australian Business Register, the official government portal for ABN registration.
Click "Apply for an ABN" — you will be taken to the online application form.
Complete the online form — the form asks about your entity type (sole trader, company, partnership, trust), your identity, your TFN, and your business activities. It typically takes around 15 minutes.
Submit the application — if your application is straightforward and the ATO can verify your identity electronically, your ABN is issued immediately upon submission.
If not immediately approved — the ATO may need to review your application manually. In this case, you will receive a reference number and the ATO will process it within 28 days.

Registration is completely free. Be wary of third-party websites charging a fee to register your ABN — there is no need to pay anyone.

What Happens After Registration

Once your ABN is issued:

It appears on the ABR public register — anyone can look up your ABN and verify that your business is registered
Link your ABN to your TFN — do this through your myGov account linked to the ATO to keep your records aligned
Consider registering for GST — if your annual turnover is $75,000 or more, GST registration is mandatory. Below that threshold it is voluntary, though it can be beneficial depending on your circumstances
Register a business name if needed — your ABN alone does not give you the right to trade under a business name other than your own legal name. If you want to operate as "Sunrise Consulting" instead of "Jane Smith", you need to register that name separately with ASIC (currently $44 for one year or $102 for three years)

ABN vs ACN

These two numbers are often confused:

ABN (Australian Business Number) — an 11-digit number used for tax and business identification. Required by all businesses.
ACN (Australian Company Number) — a 9-digit number issued by ASIC when you register a proprietary company (Pty Ltd). Only companies have an ACN. A company's ABN is typically derived from its ACN.

Most sole traders and contractors only need an ABN. You only need an ACN if you choose to operate as a registered company.

Keeping Your ABN Current

Your ABN is not a set-and-forget registration. You have ongoing obligations:

Update your details within 28 days if your business address, contact details, or business activities change
Cancel your ABN if you stop carrying on a business. You can do this at abr.business.gov.au. Cancellation takes effect immediately or on a date you specify
Using an ABN when not carrying on a business is an offence — do not maintain an ABN simply to avoid the no-ABN withholding rules if you are not genuinely running a business

Keeping accurate ABN records protects you from compliance issues and ensures the tax system reflects your actual business activities.