ABN and ACN look like two versions of the same thing, and many business owners use the terms interchangeably. They are not the same. One identifies any business for tax and commercial dealings, the other exists only because a company has been registered with ASIC.
This guide sets out the difference between an Australian Business Number and an Australian Company Number, who issues each, which business structures need which, what they cost from 1 July 2026 and where a company has to display them. Every rule was checked against the Australian Business Register, ASIC, business.gov.au and ATO pages.
It is written for people starting a business, sole traders thinking about incorporating and new company directors. If you are comparing an ABN with your personal tax file number instead, see our guide to ABN vs TFN.
Key takeaways
- An ABN is an 11-digit number issued through the Australian Business Register to any entity carrying on an enterprise.
- An ACN is a 9-digit number issued by ASIC only when a company is registered.
- A company usually needs both: the ACN on registration, then an ABN, which is often the ACN with 2 extra digits in front.
- Applying for an ABN is free; registering a company costs $636 from 1 July 2026, and a proprietary company pays a $342 annual review fee.
- A company must show its name and ACN (or ABN) on invoices, receipts, letterhead and other public documents.
ABN vs ACN at a glance
| ABN | ACN | |
|---|---|---|
| Length | 11 digits | 9 digits |
| Issued by | Australian Business Register (ABR) | ASIC |
| Who gets one | Entities carrying on or starting an enterprise in Australia, and Corporations Act companies | Companies registered under the Corporations Act |
| Cost | Free | Comes with company registration ($636 from 1 July 2026) |
| Main use | Tax, GST, invoicing, dealings with government and other businesses | Identifying the company on the ASIC register and on company documents |
| Public lookup | ABN Lookup | ASIC registers search |
Sources: ABR applying for an ABN, ASIC Australian company numbers and business.gov.au changes from 1 July 2026, checked 7 October 2026.
What is an ABN?
An Australian Business Number is a unique 11-digit number that identifies your business to the government and the community. According to the ABR, you are entitled to an ABN if you are carrying on or starting an enterprise in Australia, if you are a company registered under the Corporations Act, or if you make supplies connected with Australia’s indirect tax zone.
If your application is complete and you are entitled, you usually receive your ABN immediately online. If the ABR needs to review it, it aims to finish within 20 business days. An ABN lets you register for GST, invoice other businesses without them having to withhold tax, and claim GST credits.
Without one, a business that pays you more than $75 (excluding GST) generally has to withhold 47% of the payment, unless you give them a written statement that, for example, the work is a hobby or you are not carrying on an enterprise. If you are new to Australia, our ABN registration for new arrivals service can help you apply correctly.
What is an ACN?
An Australian Company Number is a unique 9-digit number that ASIC issues when it registers a company under the Corporations Act 2001. Only companies have ACNs. Sole traders, partnerships and trusts never receive one, even if a company acts as trustee, in which case the ACN belongs to the trustee company, not the trust.
The ACN identifies the company on the ASIC register, where anyone can check its name, status, registered office and officeholders. Once registered, a company generally applies for an ABN as well, and ASIC notes that the ABN is often the same as the ACN with 2 extra numbers at the start.
Which structures need an ABN, an ACN or both?
| Structure | ABN | ACN | Tax file number |
|---|---|---|---|
| Sole trader | Yes, if carrying on an enterprise | No | Uses the individual’s own TFN |
| Partnership | Yes | No | Separate partnership TFN |
| Trust | Yes | No (a corporate trustee has its own ACN) | Separate trust TFN |
| Company | Yes | Yes | Separate company TFN |
Source: ATO tax file number for businesses, checked 7 October 2026.
What do ABNs and ACNs cost?
Applying for an ABN is free. An ACN comes with registering a company, and business.gov.au reports that from 1 July 2026 the cost of registering a company increased from $611 to $636. A proprietary company then pays an annual review fee each year on its review date, which rose from $329 to $342 from 1 July 2026.
Those are government fees only. Setting up a company properly also involves choosing directors and shareholders, adopting a constitution or the replaceable rules, and registering for tax. Our company set-up service handles the full process.
Worked example: moving from sole trader to company
Daniel has traded as a sole trader electrician for three years under his own ABN, linked to his personal TFN.
He decides to incorporate. ASIC registers Dan Electrical Pty Ltd and issues a 9-digit ACN. The company then applies for its own ABN and its own TFN, and registers for GST because its turnover will exceed $75,000.
Daniel’s old sole trader ABN does not transfer to the company. Once he stops trading as a sole trader he should cancel it, and from then on every invoice must carry the company’s name and ACN or ABN.
Where must a company display its ACN?
Section 153 of the Corporations Act requires a company to set out its name and its ACN on documents such as invoices, statements of account, receipts, letterhead, cheques and documents lodged with ASIC. ASIC’s guidance is that the company’s ABN can be shown in place of the ACN, and that the number must be clear and readable. It is not required on business cards, envelopes or vehicles.
Rule of thumb: if a document is issued in the company’s name and asks for money or creates an obligation, put the company name and ACN or ABN on it.
What other numbers do company directors need?
Every director of an Australian company must have a director identification number before they are appointed. ASIC notes that failing to have one can attract a penalty of up to 60 penalty units, and directors appointed before 1 November 2021 had until 30 November 2022 to apply. A director ID stays with the person for life, unlike an ACN, which belongs to the company.
What happens to an ABN when a business stops?
An ABN should be cancelled when you stop carrying on the enterprise. The ABR also reviews inactive ABNs for cancellation, for example where no business income has been reported. If your circumstances change and you start trading again with the same structure, you can usually reactivate the same number; our guide on how to reactivate an ABN explains the steps. An ACN, by contrast, stays with the company until the company is deregistered by ASIC.
Common mistakes with ABNs and ACNs
- Quoting a sole trader ABN for company work. Once you incorporate, the company must invoice under its own name and numbers.
- Leaving the ACN off invoices. Section 153 requires the company name and ACN or ABN on invoices and receipts.
- Thinking a trust has an ACN. A corporate trustee has one, but the trust itself only has an ABN and TFN.
- Applying for an ABN too early. You need to be carrying on or starting an enterprise, not just planning one.
- Forgetting GST. An ABN does not register you for GST; you must register separately once turnover reaches $75,000.
FAQ about ABNs and ACNs
What is the main difference between an ABN and an ACN?
An ABN is an 11-digit number from the Australian Business Register that identifies any business entity for tax and dealings with government and other businesses. An ACN is a 9-digit number ASIC issues only to companies when they are registered under the Corporations Act.
Does a sole trader need an ACN?
No. Only companies receive an ACN. A sole trader, partnership or trust carrying on an enterprise applies for an ABN, and a sole trader uses their individual TFN for both business and personal tax.
Is a company’s ABN the same as its ACN?
Usually it is closely linked. ASIC notes that a company’s ABN is often the same as its ACN with 2 extra digits at the front. They are still separate registrations, and the company has to apply for its ABN after ASIC registers it.
How much does it cost to get an ABN or an ACN?
Applying for an ABN is free. An ACN comes with company registration, and from 1 July 2026 the fee to register a company is $636. A proprietary company also pays an annual review fee, which is $342 from 1 July 2026.
Where must a company show its ACN?
Section 153 of the Corporations Act requires a company to show its name and ACN, or its ABN in place of the ACN, on documents such as invoices, receipts, letterhead, statements of account and documents lodged with ASIC. The number must be clear and readable.
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Choosing between operating under an ABN as a sole trader and setting up a company with an ACN affects your tax, liability and paperwork. Nanak Accountants can register your ABN, set up your company and look after ongoing ASIC obligations through our company secretarial services. Call 1300 626 258, book a discovery meeting or visit nanakaccountants.com.au.
This article is general information only and is not personal tax or legal advice. Figures and rules were checked against the Australian Business Register, ASIC’s Australian company number and director ID pages, business.gov.au’s changes from 1 July 2026, and ATO pages on GST registration, no-ABN withholding and tax file numbers for businesses on 7 October 2026. Rates and thresholds change, so confirm the current position before acting.
