ABN vs ACN: Which one do you need for your business

Starting a business in Australia and not sure whether you need an ABN, an ACN, or both? The answer actually does not depend on your industry or your revenue. But it entirely depends on your business structure.

An ABN identifies your business for tax and government dealings. An ACN identifies a registered company as a separate legal entity. Sole traders carrying on an eligible enterprise commonly use an ABN but don't receive an ACN. Registered companies always receive an ACN and generally obtain an ABN once they're operating. An existing ABN can't move across when you incorporate.

Here's how they differ, when you need each, and where either of the numbers is used.

Difference between ABN vs ACN: the short answer

The difference between ABN and ACN comes down to what each number is tracking. Different regulators, different purposes, and only one of them is optional depending on how you're set up.

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For companies, the two numbers are closely linked. ASIC issues the 9-digit ACN as part of registration, and a company's ABN will often use the ACN as its last nine digits, with two additional digits at the front. So a company with ACN 123 456 789 ends up with an ABN like 36 123 456 789.

That relationship only holds for companies. A sole trader's ABN is just an ABN, with no ACN hiding inside it.

What is an ABN?

An ABN, or Australian business number, is an 11-digit number that identifies your business or organization in dealings with government and the community. You apply for it through the Australian Business Register, and you keep it for as long as you're carrying on an enterprise.

Who needs an ABN

Entitlement covers anyone carrying on or starting an enterprise in Australia, businesses making supplies connected with Australia's indirect tax zone, and companies registered under the Corporations Act.

That covers sole traders, freelancers, partnerships, trusts, and companies. One caveat: being an employee doesn't entitle you to an ABN, even if your employer calls the arrangement contracting.

Registering for an ABN isn't the same as registering for GST. GST becomes compulsory once your turnover hits AUD $75,000, with a higher $150,000 threshold for not-for-profits, and taxi, limousine, and ride-sourcing drivers must register regardless of turnover. That's a separate registration you make against the ABN you already hold.

Why do you need ABN for your business

Your ABN does more day-to-day work than your ACN. A few of the items include:

• issuing valid GST tax invoices
  
• registering for GST, PAYG withholding, and fuel tax credits
  
• dealing with the ATO and other government agencies
  
• proving you're a real trading business when a client checks ABN Lookup
  

Skip it on an invoice and there's a direct cost. Where an ABN is required but not quoted and no exception applies, the ATO generally requires the payer to withhold tax at the top rate from any payment over AUD $75 excluding GST.

That's 47% of the invoice going to the ATO instead of to you, and you only get it back when you lodge your return. Check out our guide to company tax rates to learn more.

What is an ACN?

An ACN or australian company number is a unique 9-digit number that identifies a company. ASIC issues one automatically the moment your company is registered, and it never changes for the life of the entity.

Who needs an ACN

Only companies. If you're a sole trader, a partnership, or an individual running a trust, you don't have one and you don't need one. A trust itself never gets an ACN, but if the trustee is a company rather than an individual, that corporate trustee has its own ACN, because the trustee is a registered company.

Why do you need ACN for your business

The ACN is a Corporations Act obligation rather than a tax one. Section 153 requires companies to display their full name and ACN on a defined list of documents, including everything lodged with ASIC, invoices and statements of account, orders for goods and services, business letterhead, official company notices, and cheques.

If your company's ABN is your ACN with two digits at the front, ASIC lets you display the ABN anywhere the ACN is required. One number on the letterhead instead of two.

You don't need to display the ACN on packing and labelling, machine-generated receipts, business cards, envelopes, vehicles, or TV advertisements.

Does your business need an ABN, an ACN, or both?

This is where the ABN vs ACN comparison stops being theoretical. Find your structure below, because the answer is fixed by how you're registered, not by what you do.

1. Sole traders and partnerships

If the sole trader or partnership is entitled to an ABN and is carrying on the relevant enterprise, it can have one. It doesn't receive an ACN, because it's not a registered company. You trade under your own name or a registered business name, and your ABN is the only identifier anyone asks for.

2. Companies

ACN always, and usually an ABN as well once the company is operating. ASIC registers the company and issues the ACN. Then you apply for the company's ABN, which draws on that ACN. You can do both in one pass through the government's Business Registration Service, but the sequence underneath doesn't change.

3. Trusts with a corporate trustee

The trust's business gets the trust's ABN, quoted in the trustee's name when the trustee acts for the trust. The corporate trustee has its own ACN, because it's a registered company, that's separate from anything the trust does.

The trustee doesn't automatically pick up a second ABN just for acting as trustee. It only needs one in its own right if it separately carries on its own enterprise, outside its role as trustee. Get the trust's ABN and the trustee's ACN mixed up on an invoice and your accountant will find it at year end.

What happens to your ABN when you become a company

The ABN vs ACN answer changes when your structure does, and you can't take your sole trader ABN with you.

A company is a separate legal entity from you as an individual. The ABR is explicit that moving from sole trader to company is one of the cases where you have to cancel your existing ABN and apply for a new one, and business.gov.au states plainly that a sole trader ABN can't be transferred to a new company.

So the sequence looks like this.

1. Register the company with ASIC and get the ACN
   
2. Apply for the company's new ABN, built from that ACN
   
3. Finalise your GST and other registrations tied to the old ABN, and separately cancel PAYG withholding before you cancel the ABN itself, since PAYG doesn't cancel automatically with it
   
4. Cancel the sole trader ABN once you've met your lodgement and payment obligations. GST, luxury car tax, wine equalisation tax, and fuel tax credit registrations cancel automatically when the ABN does
   
5. Update every invoice template, contract, and payment detail with the new number
   

Two things go wrong here more than anything else. Founders cancel the old ABN before the new one is active and end up trading with no valid number on their invoices. Or they keep invoicing on the sole trader ABN after the company starts trading, which means the income lands against the wrong entity.

The company also needs its own account. Before you open a business bank account, check your provider's entity-verification requirements. Some verify against the ABN, others may accept the ACN for a registered company, so confirm which applies before you apply.

Did you know: cancelling your ABN automatically cancels GST, luxury car tax, wine equalisation tax, and fuel tax credit registrations along with it. PAYG withholding doesn't cancel automatically, you have to cancel it separately, before you cancel the ABN. Whichever registrations you still need have to be set up again under the new ABN, and nobody sends you a reminder to do it.

Different use cases of ACN and ABN

Once both numbers exist, ABN vs ACN becomes a filing question rather than a registration one. Which one do you quote, and where. This is the table to keep.

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The overseas case is the one founders underestimate. Some clients, marketplaces, or counterparties may use an ABN to verify an Australian business through ABN Lookup, which is public and free. It can show the entity's legal name, entity type, GST registration, state or postcode, and any registered business names.

ASIC's company register is the equivalent for the ACN, but far fewer people outside Australia know to look there. Once they've verified you, the next question is how to pay you, and Aspire gives founders local payment details instead of a SWIFT transfer.

How to register an ABN or ACN

Registering an ABN

• Gather the information relevant to your structure. That may include TFNs for the applicant or associates, business activity details, and, for a company, the ACN
  
• If you're setting up a company, register with ASIC first, because the ABN application asks for the ACN
  
• Apply through the Australian Business Register at abr.gov.au
  
• Add GST, PAYG withholding, or fuel tax credits against the ABN once it's issued
  

Registering an ABN and registering an ACN are separate processes with separate regulators, which is the practical half of the ABN vs ACN split.

Registering an ACN

You don't apply for an ACN directly. You register the company, and the ACN comes with it.

• Choose a company name and check it's available on ASIC's register
  
• Every director needs a Director ID before their appointment, so arrange this ahead of lodging the company
  
• Lodge through ASIC or a registered agent, and pay AUD $636 for a standard Pty Ltd from 1 Jul 2026
  
• ASIC issues the ACN and the certificate of registration
  

ASIC indexes its fees to CPI every 1 July, so check the current schedule before you budget.

Two ongoing costs come attached. The annual review fee is AUD $342 for a standard proprietary company, due within two months of your review date, which is the anniversary of registration. Miss it and the late fees are AUD $102 within a month, or AUD $428 beyond that.

How to look up an ABN or ACN

• Search ABN Lookup at abr.business.gov.au for an ABN. It also shows GST registration status, useful when you're verifying a supplier
  
• Search ASIC Connect for an ACN
  
• Check the ABN is active, not cancelled, before you pay a supplier
  
• Confirm the entity name on the register matches the name on the invoice
  

Both searches are free for basic details.

Getting paid once you're registered

The ABN and ACN get you registered. Neither gets you paid. That takes a business account, and financial providers verify the legal entity, requesting the ABN, the ACN, or both depending on entity type and their onboarding requirements.

Aspire is a payment services institution built for founders operating across borders, with local NPP and BECS transfers, virtual and physical cards, spend controls, and 1% cashback on eligible FX card spend. That matters most when your clients aren't all domestic, since cross-border payments run through the same account instead of a second provider.

Frequently asked questions

What's the real difference between an ABN and an ACN?

The ABN is an 11-digit business identifier issued by the ATO through the Australian Business Register, used for tax, government, and business dealings. The ACN is a 9-digit identifier automatically issued to registered companies by ASIC. A company always has an ACN and will commonly have an ABN as well.

Is an ABN the same as an ACN?

No. An ABN is an 11-digit tax identifier for any business. An ACN is a 9-digit company identifier from ASIC. A company's ABN often contains its ACN as the final nine digits, which is why they look similar.

Can you have an ACN without an ABN?

Yes. Every registered company gets an ACN. A company may not yet have an ABN, although most operating companies obtain one for their business and tax dealings.

Can you have an ABN without an ACN?

Yes. Sole traders, partnerships and eligible trusts can have an ABN without an ACN because they are not companies.

How many digits are in an ABN and an ACN?

Eleven digits for an ABN number, nine for an ACN number. If your 11-digit number ends in the same nine digits as your company number, that's the standard company format.

Which number goes on my invoices?

It depends on the document and your entity type, not one number for every case.

• On a GST tax invoice, you need the ABN.
  
• If you're a company, s153 of the Corporations Act also requires the ACN on invoices and statements of account, unless your ABN contains the ACN in the approved format, in which case the ABN can stand in for it.
  
• Where an ABN is required but not quoted, the payer generally has to withhold tax at the top rate on relevant payments over $75 excluding GST, unless an exception applies, so quoting the ABN matters beyond just the Corporations Act requirement.
  

Do I legally need an ABN to run a business in Australia?

Not in every case, entitlement depends on whether you're carrying on an eligible enterprise. But trading without one is expensive where you're entitled to have one and don't. Where an ABN is required but not quoted, a client paying you more than AUD $75 excluding GST generally has to withhold at the top rate. Unless an exception applies, and you can't issue a valid GST tax invoice or register for GST without one.

Does a company need both an ABN and an ACN?

A registered company always gets an ACN, that's automatic on registration with ASIC. Most operating companies also obtain an ABN, since it's what you use for tax, invoicing, and government dealings. The two serve different purposes and come from different regulators, but a company's ABN often incorporates its ACN as the final nine digits. Where the ABN meets ASIC's rules, it can be displayed anywhere the ACN would otherwise be required.