How to Find My ABN (and Check Someone Else’s ABN)

Short answer: To find your ABN, search your own name or business name on ABN Lookup, the Australian Business Register’s free public search — no login is needed. If your name is common, narrow the results by state or postcode. Your ABN is also printed on your registration confirmation, invoices you have sent, your BAS and ATO letters. To check a client’s ABN, type the 11 digits into ABN Lookup and confirm the name, an active status and whether they are registered for GST.

ABN Lookup at abr.business.gov.au is run by the Australian Business Register (ABR), the government register behind every Australian Business Number, and it shows the public part of each record. The steps below apply to sole traders, contractors and anyone else who holds an ABN, and to anyone checking a supplier or client. If you have never had an ABN, see how to apply for an ABN instead; if yours has been cancelled, cancelling or updating an ABN covers getting it back.

How do I find my ABN online?

Search for your own name on ABN Lookup — it is free, public and needs no account.

1. Go to ABN Lookup and type your name into the search box. For a sole trader, the ABN is held by you as an individual, so search your legal name as well as any business name you trade under.
2. If the results list is long, use advanced search to filter by state or postcode. The ABR’s own guide describes filters for state, postcode, tax concessions and deductible gift recipient status.
3. Open the record that matches you. The ABN is at the top, with its status and the date it became active.
4. Write it down somewhere you will find it again — the top of your invoice template is the obvious place.

ABN Lookup also has a Name Lookup tool for running several name searches at once, useful if you have traded under more than one name over the years.

Search type	What you enter	Best for
Basic search	An ABN, ACN or a name	Finding your own record quickly
Advanced search	A name plus filters such as state or postcode	Common names
Name Lookup tool	Several names	Checking old trading or business names

What if I can’t find my ABN on ABN Lookup?

Usually it is the wrong name, or the ABN is not active. Work through these:

• You searched a business name that was never registered. A trading name you simply used on invoices may not be on the register. Search your personal name instead.
• Your name has changed. Search the name you used when you applied.
• The ABN was cancelled. Cancelled ABNs still appear on ABN Lookup with their status shown as cancelled. If you are trading again, you need to reapply — as a sole trader you get the same ABN back.
• You never actually got one. An application that was refused or never finished leaves nothing to find. Apply again.

If none of that works, the ABR’s ABN holders FAQs list how to contact the register, and your registered tax agent can see your details too. Never use a paid “ABN finder” service: ABN Lookup is the official source and costs nothing.

Where else is my ABN written down?

If you would rather not search, your ABN is almost certainly on paperwork you already have.

Where to look	What you will find
Your ABN registration confirmation	The ABN, sent when it was issued
Invoices you have sent	Your ABN in the header, if you followed the usual layout
Business activity statements and ATO letters	Your ABN near the top of the page
ABR online services	Your full ABN record, which you can also update
Your tax or BAS agent	Your details on their client list
Contracts and supplier forms	The ABN you gave a client when they set you up as a supplier

The ABR’s page on your ABN details explains what is held on your record and what is shown publicly.

What does an ABN look like, and how is it different from a TFN or ACN?

An ABN is 11 digits, usually written in groups as 12 345 678 901, and it is public.

Number	Digits	Who has one	Public?
ABN — Australian Business Number	11	Anyone carrying on an enterprise who has registered	Yes, on ABN Lookup
TFN — tax file number	8 or 9	Individuals and other taxpayers	No — keep it private
ACN — Australian Company Number	9	Companies only	Yes

A sole trader uses one ABN for the business and their personal TFN for tax; the TFN never goes on an invoice. A company’s ABN usually contains its ACN as the last nine digits. If you are deciding whether you need an ABN at all, read how to become a sole trader.

How do I check someone else’s ABN?

Type their ABN into ABN Lookup and compare the record with who you are dealing with.

Check	What you are looking for
ABN status	Active, and active from a date before the work was done
Entity name	The person or company you are actually dealing with, not a similar name
Business names	Any trading name on their quote or invoice
GST	”Registered from” a date — or not registered at all
Main business location	The state and postcode, which should be plausible

The GST line matters most when a supplier bills you. A business not registered for GST should not be charging you GST, and an invoice that does so will not support a GST credit claim. The ATO’s guidance on checking an ABN explains why: if a supplier does not quote an ABN and the payment is more than $75 excluding GST, you generally have to withhold the top rate of tax — 47% in 2026–27 — and send it to the ATO.

Why check a client’s ABN before you invoice them?

Because your invoice has to name them correctly, and because it tells you whether they are who they say they are.

If you are registered for GST, every tax invoice for a sale of $1,000 or more must show the buyer’s identity or ABN. Copying the exact entity name from ABN Lookup — “Harbour Lane Café Pty Ltd”, not “the café on Harbour Lane” — means the invoice matches the client’s own records and goes through their accounts team without being sent back. An ABN that shows as cancelled, or an entity name that does not match the person who hired you, is a reason to ask questions before you start work, not after. The invoice template shows where the client’s details go, and how to invoice as a sole trader covers the rest of the invoice.

Once I have it, where does Keel fit?

Your ABN belongs on every invoice and quote you send, and your clients’ details belong somewhere you can find them on the next job.

Keel: Invoice Maker & Receipts, by Ilura Technology OÜ, is an iPhone app that keeps your customers, quotes, invoices (as PDFs), receipts, expenses and business mileage together, organised by job. A quote the customer accepts becomes the invoice in one tap, and “who owes you” prepares reminder drafts that you review and send yourself. Records stay on the iPhone — no account, no bank connection, no cloud sync — and the App Store privacy label reads “Data Not Collected”. Keel does not look up ABNs or connect to the ABR or ATO, so check numbers on ABN Lookup yourself.

Keel is free with no invoice limit; free invoices carry a small “Made with Keel” footer. Keel Lifetime is a one-time purchase ($249.99 USD; the App Store shows your local price) that adds custom branding, a signature, premium templates and accountant-ready exports. Keel on the App Store. More Australian guides are in the Australia hub.

Frequently asked questions

Is ABN Lookup free to use? Yes. ABN Lookup gives free access to the public information on the Australian Business Register, and you do not need to log in. You can search by ABN, ACN or name, and use advanced search filters such as state and postcode. There is no need to pay a third-party site to “find your ABN” for you.

Can I find my ABN using my tax file number? No. ABN Lookup searches by ABN, ACN or name, not by TFN, and your TFN is private information that should never be typed into a public search or printed on an invoice. Search your legal name instead, or look at your ABN registration confirmation, your BAS or a letter from the ATO.

How do I find my ABN if I have a common name? Use ABN Lookup’s advanced search and filter by your state or postcode, which cuts the list down quickly. Then open each likely record and check the date the ABN became active against when you registered. If you trade under a registered business name, searching that name is often faster than searching your own.

What does it mean if my ABN shows as cancelled? It means the registration is no longer active, either because you cancelled it or because it was cancelled for you. You should not quote a cancelled ABN on invoices. If you are trading again with the same structure — still a sole trader — you reapply through the Australian Business Register and receive the same ABN.

How do I check if an ABN is registered for GST? Search the ABN on ABN Lookup and look at the GST line on the record. It shows whether the business is registered for GST and the date the registration started. If a supplier’s record says it is not registered, its invoices should not include GST, and you cannot claim a GST credit for GST shown on them.

Is an ABN the same as an ACN? No. An ABN is an 11-digit number for anyone carrying on an enterprise, including sole traders, and it is issued by the Australian Business Register. An ACN is a nine-digit number that only companies have. A company’s ABN usually ends with its ACN, but a sole trader has an ABN and no ACN.

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This article is general information, not tax advice. Consult a qualified Australian tax professional.