Who needs a ABN in Australia, how to register with Australian Taxation Office (ATO), what the number looks like, how to find or check one, and where it goes on your invoices.
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Updated for 2026
Last reviewed September 2026
What the ABN is
The ABN is the number Australian Taxation Office (ATO) assigns to a taxpayer in Australia. It follows you across every tax you deal with: GST, income tax and withholding. Businesses that pay you will ask for it before they release payment, because they report their suppliers to Australian Taxation Office (ATO) by this number.
ABN: 11 digits (51 824 753 556). TFN: 8 or 9 digits, never shown on invoices.
Who needs one
Individuals get a TFN; anyone running a business needs an ABN, and GST registration once turnover reaches the threshold.
How to register, step by step
Apply for a TFN through myGov or Australia Post if you do not have one.
Apply for an ABN free on the Australian Business Register (abr.gov.au); most are issued instantly.
Register for GST on the same application, or later through ATO online services, when turnover reaches $75,000.
Companies register with ASIC first and get an ACN, then the ABN.
How to find or check a ABN
ABN Lookup (abr.business.gov.au) shows any ABN's status and GST registration free.
Where it goes on your paperwork
In the invoice header next to your business name, and in the client block when the client is a registered business. Quotations and purchase orders carry it too, so the client's accounts team can match documents. The Australia invoice generator has a ABN field in both blocks.
Questions people ask
Does it cost anything to get a ABN?
Registration with Australian Taxation Office (ATO) is normally free. Agents charge for filling in the same form; pay one only if you want the time saved.
Can I invoice without a ABN?
You can write the document, but many clients will not pay an invoice that has no ABN, and you cannot charge GST without being registered. Register first; it is usually quick.
Is the ABN the same as GST registration?
Not necessarily. The ABN identifies you as a taxpayer; GST registration is a separate status you take on when turnover passes the threshold or you opt in. Some countries use one number for both, others issue a separate GST number.
How long does registration take?
Online registrations are often instant or take a few days; applications that need a visit or document checks take longer. Start before you need to send your first invoice.
Written from published tax-authority guidance and reviewed on 2026-09-03. Everything here is indicative rather than a ruling on your circumstances, and rules change. Confirm anything you rely on with Australian Taxation Office (ATO) before acting on it, and tell us if you find something out of date so we can correct it.
This guide explains the rules in general terms and is not tax advice for your circumstances. Confirm your position with a qualified adviser or with Australian Taxation Office (ATO).
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Tools for Australia
Invoices, quotations, purchase orders, credit notes and waybills in AUD, with GST and the ABN on the document. Plus a GST calculator and a salary tax calculator. Everything runs in your browser and nothing is uploaded.