ABN vs ACN (2026): The Difference, Who Needs Which, and How They Fit Together

Australian businesses juggle a lot of numbers, and the two that get mixed up most are the ABN and the ACN. They look alike, they often share nine digits, and both end up on your invoices. But they come from different agencies, prove different things and apply to different people. This guide is for sole traders weighing up a company, new company directors, partners, trustees and anyone filling in a form that asks for "ABN/ACN". It explains what each number is, who needs which, how a company's ABN is built from its ACN, and where each must appear — with worked scenarios for the common structures.

Quick answer

An ACN (Australian Company Number) is a 9-digit number ASIC gives a company when it's registered — only companies have one. An ABN (Australian Business Number) is an 11-digit number the Australian Business Register gives any entity carrying on an enterprise, including sole traders, partnerships and trusts. Most trading companies have both, and their ABN is usually the ACN with two check digits in front.

• ABN: free (free), for any business structure — apply through ABN registration

• ACN: comes with company registration — ASIC fee A$636, then A$342 a year

• Sole traders and partnerships never get an ACN

• A company can quote its ABN instead of its ACN only if the ABN's last 9 digits are the ACN

• Neither replaces a tax file number — companies, partnerships and trusts need their own TFN

What an ABN is

An Australian Business Number is an 11-digit identifier issued by the Australian Business Register (ABR), which the ATO administers. The ABR describes it as a nine-digit identifier with two check digits at the front. Its job is to identify your business when you deal with the ATO, other government agencies and other businesses: you quote it on invoices, use it to register for GST and PAYG withholding, and need it before you can register a business name with ASIC.

Any entity can hold an ABN if it is carrying on, or starting, an enterprise in Australia, or making supplies connected with Australia. That covers individuals trading as sole traders, partnerships, trusts, companies, super funds, charities and other organisations. The ABR also treats every company registered under the Corporations Act as entitled to an ABN, whether or not it is trading yet.

The ABN is free. You apply online through the ABR or the Business Registration Service; many applications are approved on screen, and those needing manual checks can take up to 20 business days. One ABN covers all the activities of one entity — a sole trader who runs a café and does weekend photography uses one ABN for both. Our ABN registration guide walks through the entitlement test and the application step by step.

What an ABN is not: it isn't proof that a business is a company, it doesn't give you any rights to a name, and it doesn't replace a tax file number. It is also public — anyone can look it up on ABN Lookup and see the entity's name, status and GST registration.

ABN vs ACN at a glance

	ABN	ACN
Full name	Australian Business Number	Australian Company Number
Digits	11 (two check digits + 9)	9
Issued by	Australian Business Register (ATO)	ASIC
Who gets one	Any entity carrying on an enterprise: sole traders, partnerships, trusts, companies, charities	Companies registered under the Corporations Act only
Cost	free	Part of company registration — A$636
Ongoing fee	None	ASIC annual review A$342
Used for	Tax, GST, invoicing, dealing with government and other businesses	Identifying the company on ASIC's register and on its public documents
Can it be cancelled?	Yes — when the business stops, is sold or changes structure	Ends only when the company is deregistered

Full name

ABN

Australian Business Number

ACN

Australian Company Number

Digits

ABN

11 (two check digits + 9)

ACN

9

Issued by

ABN

Australian Business Register (ATO)

ACN

ASIC

Who gets one

ABN

Any entity carrying on an enterprise: sole traders, partnerships, trusts, companies, charities

ACN

Companies registered under the Corporations Act only

Cost

ABN

free

ACN

Part of company registration — A$636

Ongoing fee

ABN

None

ACN

ASIC annual review A$342

Used for

ABN

Tax, GST, invoicing, dealing with government and other businesses

ACN

Identifying the company on ASIC's register and on its public documents

Can it be cancelled?

ABN

Yes — when the business stops, is sold or changes structure

ACN

Ends only when the company is deregistered

What an ACN is

An Australian Company Number is a 9-digit number that ASIC issues to every company when it is registered under the Corporations Act 2001. It identifies the company as a legal entity on ASIC's register — the thing that can own property, sign contracts, sue and be sued in its own name. You don't apply for an ACN separately; it is the output of registering a company. ASIC charges A$636 to register a proprietary company limited by shares (from 1 July 2026), and the company then pays an annual review fee of A$342 to stay on the register.

Because the ACN is tied to incorporation, sole traders, partnerships and trusts never have one in their own right. A trust may have a trustee that is a company — that trustee has an ACN — but the trust itself doesn't. If you don't choose a company name, ASIC can use the ACN as the name, which is why you sometimes see companies called "123 456 789 Pty Ltd".

Registered foreign companies and Australian bodies registering outside their home state get a cousin of the ACN: the Australian Registered Body Number (ARBN), also nine digits, issued by ASIC on registration. A foreign company that carries on an enterprise here still applies for an ABN separately.

Who needs which number

The quickest way to work out what you need is to start from your business structure, not the number. The structure decides whether there's a company at all, and only a company gets an ACN.

Sole traders need an ABN (applied for with their own TFN) and nothing from ASIC unless they trade under a name that isn't their own legal name, in which case they register a business name for A$47 (1 year) or A$108 (3 years). Registering a business name does not create an ACN. Our sole trader guide covers the rest of the set-up.

Partnerships get one ABN for the partnership plus a separate partnership TFN. There is no ACN, because a partnership isn't a company — even if one of the partners happens to be a company with its own ACN.

Trusts get their own ABN and TFN, applied for by the trustee. If the trustee is a company, that company has an ACN and its name appears on the trust's documents as "ABC Pty Ltd as trustee for the XYZ Family Trust".

Companies always have an ACN. They need an ABN as soon as they will carry on a business — invoicing, registering for GST, employing people. In practice almost every trading company applies for its ABN in the same Business Registration Service session that registers the company. A company that only holds an investment may hold an ACN without an ABN, but it is still entitled to one if it wants it.

Which numbers does your structure get?

Step 1

Choose a structure

Step 2

Sole trader / partnership / trust

ABN + TFN (individual TFN for sole traders) — no ACN

Step 3

Company

ASIC registers it → ACN; then ABR → ABN; ATO → company TFN

Step 4

Foreign company

ASIC → ARBN; ABN if carrying on an enterprise here

How a company's ABN is built from its ACN

For a company, the ABR normally builds the ABN by taking the 9-digit ACN and adding two check digits in front. ASIC's own example is a company with ACN 123 456 789 whose ABN is 36 123 456 789. That is why the two numbers look so similar on a company's invoices.

This matters for one practical rule. Under the Corporations Act a company must show its ACN on its public documents, but ASIC lets a company show its ABN instead if the ABN includes the ACN — that is, if the last nine digits of the ABN are the same as the ACN. Most companies registered in the usual way meet that test, so they print only the ABN.

If the last nine digits don't match, for whatever reason, the ABN does not stand in for the ACN and you must show the ACN as well. When you're not sure, look the company up on ABN Lookup, which lets you search by ABN, ACN or name, and compare the two numbers.

The check digits are not decoration. They let software validate an ABN before a payment goes out, so a mistyped digit is usually caught by accounting and payroll systems. If your bookkeeping software rejects a supplier's ABN, ask the supplier for it again before you pay.

Where each number must appear

The ACN rules come from the Corporations Act and ASIC; the ABN rules come mainly from tax law. Combined, they decide what goes on your paperwork.

ASIC also requires the company's full name and ACN on the first page of required documents, clearly readable, and — where several companies appear — each ACN next to its own company's name. If you trade under a registered business name, your invoices still need the legal entity's name or number so customers can tell who they're dealing with.

The ABN carries a separate, very practical consequence. If you supply goods or services to another business and don't quote an ABN, the business paying you generally has to withhold 47% of the payment and send it to the ATO. Quoting your ACN does not avoid this — only an ABN does. That's one of the most common reasons a newly registered company chases its ABN before sending its first invoice. You can produce invoices with both numbers using our free invoice generator.

Worked scenarios

The numbers become clear once you see them attached to real structures. These scenarios use illustrative numbers in ASIC's documented format.

Who holds which number — five common set-ups

1. 1

   Priya, freelance bookkeeper (sole trader)

   Priya applies for an ABN using her own TFN — free. She trades as "Priya Shah", so she needs no business name and has no ACN. Her invoices show her name and ABN.

2. 2

   Priya incorporates as Shah Ledger Pty Ltd

   Two years later Priya registers a company. ASIC charges A$636 and issues ACN 123 456 789. The ABR issues the company ABN 36 123 456 789, and the ATO gives the company its own TFN. Her old sole trader ABN is a different number for a different entity.

   Tip: If Priya stops trading as a sole trader, she should cancel the old ABN — see our cancel ABN guide.

3. 3

   Tom and Lee, café partnership

   The partnership gets one ABN and a partnership TFN. There is no ACN. Each partner still lodges their own individual return, using their individual TFN, for their share of the profit.

4. 4

   The Nguyen Family Trust with a company trustee

   Nguyen Holdings Pty Ltd is the trustee: it has an ACN. The trust has its own ABN and TFN. Documents read "Nguyen Holdings Pty Ltd ACN 987 654 321 as trustee for the Nguyen Family Trust ABN …".

5. 5

   A UK company opening a Sydney sales office

   It registers as a foreign company with ASIC and receives a 9-digit ARBN, appoints a local agent, and applies for an ABN because it now carries on an enterprise in Australia.

The second scenario is where people trip. When Priya incorporates, nothing "converts" her sole trader ABN into a company ABN. The company is a new legal person with a new ACN, a new ABN and a new TFN. Her clients need updated details, her bank account should move to the company's name, and her GST registration for the sole trader business needs to be dealt with. Our company registration guide covers the director ID she must hold first and the A$342 annual review she'll pay every year after.

The trust scenario has the most numbers: an ACN for the trustee company, an ABN and TFN for the trust, and frequently a separate ABN for the trustee company if it also trades in its own right. Each entity lodges its own return under its own TFN.

Do you need an ABN, an ACN, or both?

Most people asking "ABN or ACN?" are really asking "should I be a sole trader or a company?" The numbers follow the decision, so it helps to compare what each route costs and gives you.

Staying a sole trader means one free ABN, your own TFN, unlimited personal liability and tax on profit at your individual rates. Registering a company means an ACN and ABN, a separate company TFN, the A$636 registration fee and A$342 a year, director duties, and company tax — 25% for a base rate entity. In return you usually get limited liability and the ability to keep profit in the company at the company rate.

A few situations where people think they need an ACN but don't:

• You want to protect your business name. An ACN doesn't do that, and neither does a business name registration. Only a registered trade mark gives exclusive rights.
• A big client asked for "your ACN". If you're a sole trader or partnership, you don't have one — give your ABN and say what structure you are. Many forms say "ABN/ACN" because they expect either.
• You want to look established. A company costs more each year and adds obligations. If the reason is image, a business name and good branding cost far less.

And situations where an ABN alone isn't enough: you want limited liability, you're bringing in co-owners or investors who want shares, or your profit is high enough that retaining it in a company makes sense. That's a company decision, and the ACN comes with it. Get an accountant to model the tax before you register, because moving assets from a sole trader to a company can trigger tax consequences.

Keeping the details right after registration

Both registers expect you to keep them current, on separate deadlines and through separate portals.

For your ABN, you must update your details on the ABR — address, contacts, business activity, associates — within 28 days of a change. You do this through ABR online services with your myID, or through your tax agent. If the business stops, is sold or changes structure, you cancel the ABN rather than leave it dormant.

For your company, changes such as a new registered office, director or shareholder are notified to ASIC, generally within 28 days. Every director needs a director ID before they're appointed, and from 1 July 2027 companies must provide their directors' IDs to ASIC. ASIC does not update the ABR for you, and the ABR does not update ASIC, so a change of address usually means two updates.

ABN and ACN housekeeping

0/6

• Check that your company's ABN contains its ACN — if not, show both on public documents
• Put the company name and ACN (or ABN) on invoices, receipts, orders and letterhead
• Quote your ABN to every business customer to avoid 47% no-ABN withholding
• Update ABR details within 28 days of a change
• Notify ASIC of company changes within 28 days
• Keep the company's TFN private — unlike the ABN and ACN, it is never published

Share Print

Common mix-ups and how to fix them

Quoting the ACN on a GST tax invoice. A tax invoice must show the seller's ABN. If you've been sending invoices with only an ACN, reissue them with the ABN so your customers can claim their GST credits.

Using the sole trader ABN for the new company. Invoices issued by the company must carry the company's details. Money paid to the company but invoiced under the old ABN muddles both entities' income and GST. Fix it by issuing adjustment notes and new invoices from the company, and talk to your accountant about the period of overlap.

Assuming a business name makes you a company. Registering "Harbour Plumbing" with ASIC doesn't create a company, an ACN or limited liability. The business name holder is still you (or your partnership or trust).

Leaving an ABN active after incorporating. If the sole trader business has stopped, an active ABN keeps lodgment obligations alive and can confuse customers who look you up. Our guide to cancelling an ABN covers the final BAS and GST steps.

Confusing ABN and TFN. Your TFN is confidential; your ABN and ACN are public. Never put a TFN on an invoice. The business TFN guide explains which entities need their own TFN and how to apply with the ABN.

Official links

• ASIC — Australian Company Number (ACN)Where the ACN must appear and the ABN-for-ACN rule
• ABR — ABN entitlement
• ABN Lookup — search by ABN, ACN or name
• Business Registration Service — company, ABN, TFN, GST in one session
• ASIC — ARBN definition
• ASIC — fees for commonly lodged documents

What to do next

If you're starting out as a sole trader, partnership or trust, you only need the ABN — apply for it free through our ABN registration guide, then check whether you need a business name. If you're forming a company, follow the company registration guide: director IDs first, then the company (and its ACN), then the ABN — the ABN application lets you request the company's TFN and GST registration at the same time. Brainstorm a name with our business name generator and send your first compliant invoice with the invoice generator.

This is general information, not legal or tax advice — confirm on the official source or with a professional.

Frequently asked questions

What is the difference between an ABN and an ACN?

An ACN is a 9-digit number ASIC gives a company when it is registered under the Corporations Act; only companies have one. An ABN is an 11-digit number the Australian Business Register gives any entity carrying on an enterprise — sole traders, partnerships, trusts and companies. The ACN identifies the legal entity on ASIC's register; the ABN identifies the business for tax and government dealings.

Does a sole trader need an ACN?

No. Only companies get an ACN, because it is issued on registration with ASIC. A sole trader needs an ABN (free from the Australian Business Register), uses their own tax file number and registers a business name only if trading under a name other than their own. If you later incorporate, the new company gets an ACN and its own, different ABN.

Is the ABN the same as the ACN with two extra digits?

For most companies, yes. A company's ABN is usually its 9-digit ACN with two check digits in front — ASIC's example is ACN 123 456 789 and ABN 36 123 456 789. When that's the case, the company can quote its ABN wherever the law asks for the ACN. If the last nine digits don't match, you must show the ACN separately.

Does a company need both an ABN and an ACN?

Every company has an ACN from the moment ASIC registers it. It needs an ABN as well if it will carry on a business, register for GST, employ staff or invoice other businesses — which is almost every trading company. A Corporations Act company is entitled to an ABN, and you can apply in the same Business Registration Service session that registers the company.

Do I need to put my ACN on invoices?

Yes, if you are a company. ASIC requires the company's name and ACN (or an ABN that contains the ACN) on invoices, statements of account, receipts other than machine-produced ones, orders, letterhead and other public documents. Business cards, envelopes, packaging and vehicles are exempt. GST-registered sellers also need their ABN on tax invoices.

What is an ARBN?

An Australian Registered Body Number is a 9-digit number ASIC gives a foreign company or a registered Australian body when it registers to carry on business here. It plays the same role as an ACN for those bodies. If the foreign company carries on an enterprise in Australia, it applies separately for an ABN.

Sources & verification

Figures on this page were checked against the sources below when it was last reviewed on 11 October 2026. Each rate and limit is stored once with its own official source and review date, and official update channels are monitored daily so changes are picked up. How we verify

1. 1.Australian Company Number (ACN) — ASIC · accessed 11 October 2026
2. 2.ABN basics FAQs — Australian Business Register · accessed 11 October 2026
3. 3.ABN entitlement — Australian Business Register · accessed 11 October 2026
4. 4.Australian Registered Body Number (ARBN) — glossary — ASIC · accessed 11 October 2026
5. 5.Register a foreign company in Australia — ASIC · accessed 11 October 2026
6. 6.Fees for commonly lodged documents — ASIC · accessed 11 October 2026
7. 7.Register for a tax file number — business.gov.au · accessed 11 October 2026
8. 8.Statement by a supplier not quoting an ABN — Australian Taxation Office · accessed 11 October 2026
9. 9.Director identification numbers (director IDs) — ASIC · accessed 11 October 2026