An Australian Business Number is an eleven-digit identifier for your business. You apply for it through the Australian Business Register at abr.gov.au, it is free, and if your identity details match cleanly the number is usually issued immediately on submitting the form. You need to be carrying on an enterprise in Australia — or to have started the arrangements to — before you are entitled to one.
Who is entitled to an ABN?
Entitlement rests on whether you are carrying on an enterprise, not on how much you earn. In practice that means you are supplying goods or services with a commercial intent — quoting, invoicing, advertising, repeating the work. You are not entitled if:
- You are really an employee. An employer cannot make you get an ABN so that they can treat you as a contractor. Whether you are an employee or a contractor is decided by the substance of the arrangement, not by the paperwork.
- It is a hobby. Occasional sales with no profit motive are not an enterprise, and you neither declare that income nor claim those expenses.
- You are only planning it. You may apply once you have started the arrangements — registering a domain, buying tools, taking bookings — but not on an idea alone.
Everyone who is entitled can have one, in every structure: sole traders, partnerships, companies and trusts. A sole trader gets one ABN, in their own name, and it stays with them across every business they run as a sole trader.
What to have ready before you apply
The form is short if you have these to hand, and frustrating if you do not:
- Your Tax File Number, and the TFNs of any partners, directors or trustees. Supplying it is not compulsory, but leaving it out is the most common reason an application gets referred for manual checking.
- Your identity details exactly as the ATO holds them — full legal name and date of birth. A name that does not match causes a referral.
- Your business structure, decided before you start. The form branches on it and it is not a field you want to guess at.
- Your main business activity, which you select from a standard list of industry classifications. Pick the closest; it is used for statistics, not to limit what you may do.
- The date you want the ABN to start, which can be up to six months ahead but should not be backdated past when you actually began.
- Contact and business address details, plus an authorised contact person.
- An ACN, if you are applying for a company — you register the company with ASIC first, then apply for its ABN.
Do not pay for an ABN
Applying directly through the Australian Business Register costs nothing. There are commercial sites that will complete the same form on your behalf for a fee, and they rank well in search results because they can afford to advertise on a term that the free government service does not bid on. They are not scams and they are not necessary. Go to abr.gov.au, or ask your registered tax agent to do it as part of setting you up.
How long does it take?
There are three outcomes. Most applications are approved immediately and the number appears on screen — write it down, and expect the written confirmation separately. Some are referred for manual review, usually because the identity details did not match or the ABR wants more information about the enterprise; the ABR's published timeframe for those is around 20 business days, and it will contact you if it needs anything. A few are refused, in which case you are given the reason and the right to have the decision reviewed.
Do not start invoicing on the assumption that a referred application will come through. Until the number exists, no-ABN withholding applies.
What happens if you invoice without an ABN?
When one business pays another for goods or services and no ABN is quoted on the invoice, the payer is generally required to withhold tax at the top rate from the payment and send it to the ATO. You are not out of pocket permanently — it is credited when you lodge your return — but you are short most of the money for the rest of the financial year, and it makes you awkward to deal with.
There are exceptions, including where the payment is under a small threshold or the supply is private or domestic in nature. Do not build a business around the exceptions. Put your ABN on every invoice — it is one of the things a valid tax invoice must show anyway.
What an ABN is not
| Not the same as | What it actually is |
|---|---|
| A Tax File Number | Your TFN is your personal tax identifier and stays private. An ABN is public and identifies the business. |
| An ACN | An Australian Company Number is issued by ASIC when you register a company. Only companies have one, and they still need an ABN as well. |
| A business name | A registered business name is the trading name, registered separately with ASIC. You need an ABN before you can register one. |
| GST registration | A separate registration with its own $75,000 threshold. Having an ABN does not mean you charge GST. |
In particular, having an ABN does not mean you charge GST. GST is a separate registration with its own threshold — whether you need it is a different question.
Keeping the ABN current
Your ABN details are public through ABN Lookup, and you are required to keep them up to date — changes must be notified within 28 days of you becoming aware of them. That covers your address, your contact details, your authorised contacts and your main business activity.
If you stop trading, cancel the ABN rather than leaving it open. An inactive ABN attached to no activity gets flagged, and the ABR periodically cancels ABNs that show no signs of business. If you start again later, you can reactivate the same number.
Checking someone else's ABN
ABN Lookup is free and public, and it tells you two things worth knowing before you pay a supplier's invoice: whether the ABN is active, and whether that business is registered for GST. If a supplier has charged you GST but is not registered for it, there is no GST there for you to claim back on your BAS — and claiming it anyway is an error the ATO does check.
Related reading
- How to start a business in Australia — where the ABN fits in the order
- Sole trader, partnership, company or trust? — decide this before you apply
- Do I need to register for GST? — the separate registration
- How to invoice with GST — putting the ABN on the invoice
- ABN vs ACN — the number companies get as well
- How to register a business name — the registration that needs the ABN first
Frequently asked questions
Nothing. Applying through the Australian Business Register at abr.gov.au is free, and so is cancelling or reactivating one. Commercial services that offer to lodge the application for you charge a fee for something the government provides at no cost.
Most applications are approved immediately and the number is displayed as soon as you submit. If the application is referred for manual review — usually because identity details did not match — the Australian Business Register works to a published timeframe of around 20 business days and will contact you if it needs more information.
As a sole trader, no. You get one ABN in your own name and it covers every business you run in that capacity, no matter how many trading names you register against it. Separate ABNs exist for separate legal entities — a company, a partnership or a trust each has its own.
It depends on whether the activity is a business or a hobby, not on whether it is your main income. If you are supplying goods or services with a commercial intent, and doing it repeatedly, you are carrying on an enterprise and should have an ABN — regardless of how small it is or how many other jobs you have.
Cancel it. You are required to cancel an ABN within 28 days of ceasing business, and leaving an unused one open invites the Australian Business Register to cancel it for inactivity. If you start trading again later you can reactivate the same number rather than applying afresh.
Sources
Entitlement rules, application requirements and processing timeframes come from the Australian Business Register and the Australian Taxation Office. Requirements change — confirm the current position at abr.gov.au or ato.gov.au, or with a registered tax agent. Balaana is bookkeeping software, not a tax agent — this article is general information, not personal tax advice.