ABN vs ACN: What's the Difference and Which Do You Need — 2026 AU Guide
An ABN (Australian Business Number) identifies your business for tax and trading purposes, while an ACN (Australian Company Number) is a unique identifier issued only when you register a company through ASIC. Most sole traders and partnerships need only an ABN, but if you incorporate a company, you will receive both an ACN and an ABN.
What Is an ABN and Who Issues It?
An ABN is an 11-digit number that identifies your business or enterprise to the government and to other businesses. It is issued by the Australian Business Register (ABR), which is administered by the Australian Taxation Office.
You use your ABN when invoicing customers, registering for GST, dealing with the ATO, and quoting your business identity to suppliers. Without an ABN, other businesses may be required to withhold tax from payments they make to you, which can complicate your cash flow significantly.
Almost any type of business structure can hold an ABN: sole traders, partnerships, trusts, and companies are all eligible. The key requirement, according to the Australian Business Register, is that you carry on an enterprise or are planning to do so. A hobby that generates occasional income generally does not qualify, so it is worth checking your situation with an accountant or the ATO before applying.
Applying for an ABN is free through the ABR's online portal, and in many straightforward cases the number is issued instantly. More complex applications, particularly those involving trusts or non-resident entities, may take longer.
What Is an ACN and Who Issues It?
An ACN is a nine-digit number issued exclusively by the Australian Securities and Investments Commission (ASIC) when you register a new company under the Corporations Act 2001. It identifies the legal entity of the company itself, separate from any business name or ABN it might hold.
Your ACN must appear on all public documents, registered office signage, and negotiable instruments such as cheques. ASIC uses it to track the company's compliance obligations, such as annual review fees, director disclosures, and lodgement of financial reports where required.
Unlike an ABN, you cannot choose whether or not to have an ACN. If you register a company, you automatically receive one. Sole traders and partnerships, on the other hand, will never receive an ACN because they are not separate legal entities under the Corporations Act.
Key Differences at a Glance
Understanding the practical distinctions between the two identifiers helps you plan your structure before you register. The most important differences come down to who issues them, what structure they relate to, and what obligations they trigger.
- Issuing authority: The ABR issues ABNs; ASIC issues ACNs. - Who needs one: Any business enterprise may need an ABN; only registered companies receive an ACN. - Legal significance: An ACN denotes a distinct legal entity with its own rights and liabilities under the Corporations Act 2001. - Display requirements: Companies must display their ACN on public documents; ABN display is required on tax invoices and business correspondence. - Cost: Applying for an ABN is free via the ABR. Registering a company with ASIC attracts a government fee, the current amount for which is published on ASIC's fees page. Because fees change, always verify the current rate directly with ASIC before budgeting.
For a broader breakdown of registration expenses, see our cost guide.
Which One Do You Actually Need?
The answer depends almost entirely on your chosen business structure.
Sole trader: You need only an ABN. You trade under your own name or a registered business name, and there is no separate legal entity involved. Partnership: The partnership itself requires an ABN. Individual partners do not receive a separate identifier from the ABR just for being a partner. Trust: A trust typically needs an ABN in the name of the trustee acting in their capacity as trustee of the trust. No ACN is involved unless the trustee is itself a company. Company: Registering a company through ASIC automatically generates an ACN. ASIC then facilitates the simultaneous application for an ABN, so most new companies receive both numbers at registration. The business.gov.au guide to registering a company explains this process step by step. Tip for growing businesses: Many sole traders eventually incorporate to limit personal liability or to bring on investors. At that point, the new company entity will need its own ABN linked to its ACN, while the old sole trader ABN may be cancelled or retained for a different purpose. Speak to a registered tax agent or business adviser before making that transition.How to Apply: Practical Steps in 2026
Applying for an ABN is handled through the Australian Business Register's online portal. You will need your Tax File Number (TFN) or, for companies and trusts, the entity's TFN, along with details of your business activities and structure.
Registering a company and obtaining an ACN is done through ASIC's online portal. Many businesses use a registered agent or company registration service to streamline this process, particularly when the ownership structure involves multiple shareholders or complex share classes.
For a curated list of professional services that assist with Australian company formation, browse our best company registration services in Sydney or explore the full directory at /best/.
Our methodology page explains how we evaluate and rank the services listed in our directory.
Common Mistakes to Avoid
Several avoidable errors trip up new business owners during registration.
Applying for an ABN without a genuine enterprise: The ABR assesses whether you actually carry on a business. Applying prematurely or for hobby activities can result in rejection or, worse, a later audit. Forgetting to display the correct identifier: Companies must show their ACN (or ABN if it incorporates the ACN) on invoices, contracts, and correspondence. Omitting it can attract penalties under the Corporations Act. Assuming an ABN replaces an ACN: Some new business owners believe that once they have an ABN for their company, the ACN is optional. It is not. Both identifiers serve distinct statutory functions. Not updating ABN details when circumstances change: If your business structure, address, or activities change materially, you are obliged to update your ABN details with the ABR within a prescribed timeframe.---
Frequently Asked Questions
Q: Can a sole trader apply for an ACN? No. An ACN is issued only when a company is registered with ASIC under the Corporations Act 2001. Sole traders operate under their own legal identity and require only an ABN. Q: Do I need to display both my ABN and ACN on invoices? If your ABN was derived from your ACN (which is the case for most companies), displaying the ABN alone is generally sufficient for invoice purposes. However, you should confirm display requirements with a qualified adviser or refer to ASIC's guidance and the ATO's invoicing rules, as obligations differ by document type. Q: How long does it take to get an ABN? Many straightforward applications through the ABR portal are processed instantly. More complex applications can take several weeks, particularly for non-resident entities or those with atypical structures. Q: Is there a fee to apply for an ABN? Applying for an ABN directly through the Australian Business Register is free. If you use a third-party service or agent to assist with the application, that service may charge its own fee, separate from the government's process.---
Sources
- Australian Business Register (ABR) - Australian Securities and Investments Commission (ASIC) - Australian Taxation Office (ATO) - business.gov.au — Registering a Company - Corporations Act 2001 (Commonwealth)
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Information in this article is general only and not legal or tax advice. Verify the details with the linked sources or an appropriately qualified Australian professional before relying on them.
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