An ABN identifies an eligible business or organisation for tax and everyday dealings with government and suppliers, while an ACN identifies a company that is registered under the Corporations Act. If you operate as a sole trader, partnership or trust you normally need an ABN but never receive an ACN because you are not a company. If you establish a company you automatically receive an ACN and then usually apply for an ABN as well so the company can trade and comply with tax obligations.
ABN vs ACN at a glance
| Identifier | What it identifies | Who may receive it | Main purpose |
|---|---|---|---|
| ABN | Any enterprise that meets the eligibility rules in the Goods and Services Tax Act | Sole traders, partnerships, trusts, companies, non-profits, super funds and some property ventures | Lets the entity register for GST, include the number on invoices, claim credits, deal with government bodies and confirm identity in commercial transactions |
| ACN | A company that has completed registration with ASIC under the Corporations Act | Proprietary limited companies, public companies, companies limited by guarantee and other company types | Confirms corporate identity, links the company to ASIC registers, appears on official documents and helps creditors and regulators track compliance |
A company can therefore quote two distinct numbers. The ACN proves that the entity is in fact a registered company. The ABN lets the same company interact with the Australian tax system and with customers that expect an ABN on invoices.
What an ABN really is
The Australian Business Number is an eleven-digit identifier that sits in the national Business Register which the Australian Taxation Office administers. The digits follow a specific mathematical formula that lets automated systems verify the number instantly. When an enterprise applies, the Registrar checks whether the activities meet the legal definition of carrying on an enterprise which appears in section 9-20 of the Goods and Services Tax Act. Promotion before opening the doors, securing licences or negotiating a lease can all count as enterprise activity for entitlement purposes.
Holding an ABN offers several practical advantages. It avoids withholding on payments from other businesses that would otherwise need to deduct tax. It allows registration for goods and services tax once annual turnover reaches the threshold which currently sits at 75,000 dollars for most businesses. It also appears on official purchase orders, invoices and receipts which gives trading partners confidence that they are dealing with a genuine entity. When business details change there is a legal duty to update the register within twenty-eight days so that the information stays current.
Sole traders apply using their own tax file numbers and personal identity documents. Partnerships lodge a single application that covers the firm rather than the individual partners. Trustees or responsible persons submit the application on behalf of trusts and super funds. Fees do not apply for the ABN itself though professional advisers may charge for assistance.
Failing to quote an ABN where required or applying without real entitlement can trigger compliance action. The Registrar may cancel the number, backdate the cancellation and refer serious cases for prosecution. The ATO can impose administrative penalties if the entity uses the number to claim credits or refunds that are not due. These enforcement mechanisms protect the integrity of the register and the wider tax system.
What an ACN really is
The Australian Company Number is a nine-digit identifier that ASIC issues at the exact moment a company becomes incorporated. Unlike an ABN, the ACN has no direct link to the tax system. Instead it anchors the company to its corporate registry obligations. The number must appear on every public document, including letterheads, email signatures, invoices, statements and orders, unless the document already displays the ABN in a way that incorporates the ACN or unless an exemption applies. The requirement also extends to the common seal if a company still uses one.
Companies are separate legal persons with perpetual succession and limited liability for most members. Because they can outlive their founders and accumulate substantial obligations, the law imposes strict disclosure rules. The ACN lets ASIC, creditors, employees and investors track the company’s lodgements, financial reports, share structure and enforcement history. Late financial statements, failure to update addresses, ignoring annual review fees or omitting the ACN from documents can each lead to infringement notices or court action. Directors can face personal liability or even disqualification if they allow serious breaches to persist.
Registering a company requires at least one director who holds a director identification number, a carefully chosen name or the option to operate solely under the ACN, a physical registered office in an Australian state or territory, and a set of internal governance rules. The registration fee is payable to ASIC. Once the certificate of registration arrives the company can then apply for an ABN through the Business Registration Service so the two identifiers can operate side by side.
Do you need an ABN, an ACN or both
Consider the nature of your enterprise first. A graphic designer who works alone and trades under her own name is a sole trader. She needs an ABN because she issues invoices and wants to avoid payer withholding. She does not receive an ACN because she has not formed a company. A partnership of two friends running a café applies for one ABN that covers the partnership. Again, no ACN appears because the partners have not set up a company. A family trust that invests in property obtains an ABN for the trust so it can register for GST on commercial rents. The trust does not need an ACN unless it sets up a corporate trustee that acts as a separate company.
By contrast, a start-up that incorporates as CoffeeTech Pty Ltd receives an ACN from ASIC on registration day. The founders then lodge one additional online form to obtain an ABN so the company can trade under the same name and meet its tax obligations. If those founders later create a second company as a property holding vehicle, that new company receives a fresh ACN and must apply for its own ABN even if the two companies share directors.
Changing structure can also alter the registrations required. A consultant who moves from sole trader to proprietary limited company has to cancel or update the sole trader ABN, establish the company, obtain the new ACN and then apply for a new ABN in the company name. Contracts, insurance policies and supplier agreements must reference the correct entity and its corresponding identifiers once the change occurs.
ABN, ACN, TFN and business name explained
The tax file number often appears alongside ABN and ACN in online searches. A TFN is a confidential identifier that individuals, companies and certain trusts receive for income tax purposes. It should never appear on invoices or public documents because privacy laws protect it. An ABN, by comparison, is intentionally public and searchable. When you look up a supplier on the ABN Lookup service you will never see the TFN.
A business name is yet another concept. Registering Coffee Crew as a business name simply grants the right to trade under that name. The registration does not create a company and does not provide an ACN. The underlying entity, whether a sole trader, partnership, trust or company, still needs its own appropriate identifiers. Many small ventures therefore hold a trio of registrations. The entity has an ABN, the trading name is on ASIC’s business names register and the company has an ACN if the structure chosen is corporate.
Understanding the distinction between these identifiers prevents expensive mistakes when quoting numbers on documents or lodging returns. Clients often assume that a business name confers limited liability or that an ABN confirms incorporation. Neither assumption is correct.
Where to find your ABN or ACN
If you have misplaced your confirmation letter you can still recover the details easily. The ABN appears on every activity statement, GST statement, many bank records and often on your own invoices if you have been following best practice. The quickest public method is the ABN Lookup website which the government maintains. Searching by business name, entity name or the eleven-digit number itself reveals the current registration status and historical data such as previous names or cancellation events.
The ACN can be found on the certificate of registration, share certificates, ASIC annual review paperwork, the company extract available from ASIC and on the company pages of commercial information providers. Because companies must display the ACN on most correspondence, many people locate it in email footers or letterheads. If you need to verify a supplier, the ASIC Companies Register offers free summary extracts that include the ACN, type of company, date of registration and registered office details. Paid extracts provide the full share structure and histories.
Common mistakes and how to avoid them
One frequent error is assuming every business needs an ACN. Only companies do. Another error is treating a business name registration as evidence of limited liability. Liability rests with the underlying entity, not with the name. Many sole traders discover this only when served with a statement of claim bearing their personal name. Quoting an incorrect or cancelled ABN on tax invoices creates another trap. Customers who rely on that invoice may withhold payments or even refuse to deal further if they uncover inaccuracies.
For companies, omitting the ACN from documents opens the door to ASIC penalties. Forgetting to pay the annual review fee can lead to late fees that compound each month. Over time ASIC can deregister the company entirely, causing bank accounts to freeze. Where a venture changes structure, failing to update contracts, website terms and stationary with the new identifiers can result in parties suing the wrong entity and claims being struck out.
Careful housekeeping and periodic checks on the official registers help prevent these problems. Using the same email address for both ABN and ACN correspondence lets you receive reminders about lodgement dates and any proposed cancellation actions.
Frequently asked questions
Is an ABN the same as an ACN
No. An ABN identifies an eligible business or organisation within the tax system while an ACN identifies a company registered with ASIC.
Does a sole trader need an ACN
No. A sole trader is not a company and therefore never receives an ACN. The sole trader typically needs an ABN instead.
Does every company need an ABN
Most companies apply for an ABN because they engage in trading activity or need to register for GST. The law does not grant an ABN automatically with the ACN so a separate application remains necessary.
Can a business hold both an ABN and an ACN
Yes. A company almost always holds both numbers. The ACN proves incorporation. The ABN enables tax and commercial transactions.
Is a business name the same as a company
No. A business name is simply a registered trading name. It does not create a separate legal entity and does not provide an ACN.
Where can I look up an ACN
You can search the ASIC Companies Register online using the company name or the nine-digit number. Free summary information is available for every registered company.
Where can I look up an ABN
Use the government ABN Lookup service and search by name or number. The database shows current and past status and linked business names.
Do I need an ABN to issue invoices
Businesses generally include an ABN on invoices. If you supply goods or services without quoting an ABN the payer may withhold tax unless an exemption applies.
Does moving from sole trader to company require a new ABN
Yes. When you incorporate you create a new legal entity. The new company must obtain its own ABN and ACN. The old sole trader ABN should be cancelled or updated to reflect cessation of the enterprise.
Need help choosing the right structure and registrations
Selecting the correct identifier is only one step toward running a compliant and efficient venture in Australia. If you are still unsure whether to remain a sole trader, form a partnership, establish a trust or register a company, professional advice can save both time and money. A qualified business adviser or accountant can review your goals, risk profile and tax position, then guide you through the application process for ABNs, ACNs, GST, PAYG withholding, business names and licences. Reaching out early avoids the cost of correcting mistakes after trading has commenced and helps you focus on growth with confidence that your legal foundations are sound.
