ACN vs ABN: Understanding The Difference

When you’re starting a business in Australia, it’s easy to get lost in the acronyms - especially when it comes to your registration numbers. Two of the most common are the ACN (Australian Company Number) and the ABN (Australian Business Number). They’re related, but they do different jobs.

If you’ve been wondering “Do I need an ABN or ACN?”, “Is ACN the same as ABN?”, or “What happens if I have an ACN but no ABN?” - you’re in the right place. In this guide, we’ll break down what each number means, who needs them, when they’re used, and how to keep things compliant as you grow.

Our goal is to help you set up the right way from day one, and avoid common pitfalls that trip up new business owners.

What Is An ACN In Australia?

An ACN (Australian Company Number) is a unique nine-digit number issued by ASIC (the Australian Securities and Investments Commission) when you register a company.

• What it identifies: Your company as a separate legal entity. Think of it as the company’s official ID under the Corporations Act.
• Who gets one: Companies only - for example, proprietary limited (Pty Ltd) or public companies. Sole traders, partnerships and most trusts don’t get an ACN unless the trustee itself is a company.
• Where it appears: Companies must display their ACN on certain company “public documents” and correspondence (for example, statements, notices and order forms). Many businesses also include it on contracts and websites for clarity and good practice.

If you’re moving towards a company structure, it can help to map out the process and obligations early. Registering a company is a formal step - you’ll appoint directors, adopt governing documents and receive your ACN as part of a Company Set Up.

What Is An ABN?

An ABN (Australian Business Number) is an 11-digit number that identifies your business to the government, other businesses and the community. It’s recorded on the Australian Business Register and used widely for tax and trading purposes.

• What it identifies: Your business dealings for tax and commercial purposes (for example, on invoices and purchase orders) and when dealing with government.
• Who gets one: Most businesses carrying on an enterprise in Australia - including sole traders, partnerships, companies and some trusts - should register for an ABN.
• Why it matters: You’ll use an ABN to issue valid tax invoices, register for GST (if required), and to avoid payers withholding tax from your payments under the “no ABN withholding” rules (subject to exceptions).

Tax settings (like GST registration) can depend on your turnover and activities, so it’s wise to check these with your accountant. The information here is general in nature.

ACN vs ABN: Key Differences, Display Rules And FAQs

The simple way to remember it is this: an ABN is about trading and tax; an ACN is about being a registered company. Many companies have both - but not every business is a company.

• Purpose: An ABN identifies your business for tax and commercial interactions nationwide. An ACN identifies a company as a legal entity regulated by ASIC.
• Who needs them: Most active businesses should hold an ABN. Only companies registered with ASIC receive an ACN.
• Format: ABN = 11 digits. ACN = 9 digits. For companies, the last nine digits of the ABN often match the ACN (the first two digits of the ABN are a checksum).

Do I Need Both Numbers?

It depends on your structure. If you operate as a sole trader or partnership, you’ll generally only need an ABN. If you operate through a company, you’ll have an ACN and should also register an ABN if you’re trading.

Can You Have An ACN Without An ABN?

When you register a company, ASIC issues an ACN immediately. If your company will trade (issue invoices, enter supply contracts, etc.), it should also obtain an ABN. Without an ABN, payers may be required to withhold tax from your payments (unless an exception applies), and you won’t be able to register for GST.

Is The ACN The Last 9 Digits Of The ABN?

Not exactly - but often close. For companies, the ABN commonly incorporates the ACN, with two leading digits as a checksum. They remain separate identifiers with different legal purposes.

Display Rules: Where Do These Numbers Go?

• ACN on company documents: Companies must display their ACN (or ABN if they have one and choose to use it) on specific “public documents” and certain correspondence under the Corporations Act and associated regulations. It’s also good practice to include it on your website and contracts so counterparties can identify the company.
• ABN on tax invoices: To issue a valid tax invoice and deal properly with GST, your ABN should appear on invoices. If you don’t quote an ABN to payers when required, they may need to withhold tax from your payment under withholding rules.

ABN vs Business Name vs Company Name

These are all different concepts. Your ABN identifies your business dealings. A business name is the trading name you register to the public. Your company name is the legal name of the company registered with ASIC. If you’re juggling these terms, it can help to review Business Name vs Company Name to understand how they fit together.

ARBN vs ACN - What’s The Difference?

An ARBN (Australian Registered Body Number) is issued to certain registered bodies (for example, some foreign companies or Australian registrable bodies) that are registered to operate in Australia but are not incorporated here. If you’ve set up a standard Pty Ltd or Australian public company, you’ll receive an ACN.

Do You Need An ACN, An ABN, Or Both?

Your business structure drives which registrations you need. Here’s a quick guide:

• Sole Trader: You operate as an individual. You’ll generally need an ABN to trade under your business, and you can optionally register a business name for branding. No ACN is issued because you’re not a company.
• Partnership: Two or more people carry on business together. The partnership should hold its own ABN. No ACN unless the partners use a company as the partner entity.
• Trust: The trustee applies for an ABN on behalf of the trust. If the trustee is a company, that company will have its own ACN as well.
• Company (Pty Ltd or public): You’ll receive an ACN when you register with ASIC. If the company will trade, you should also apply for an ABN for invoicing, GST and commercial dealings.

Companies come with added benefits (like limited liability) and added responsibilities (like director duties and ASIC reporting). If you’re considering the switch, factor in governance documents (for example, a Company Constitution) and director requirements such as Australian resident director rules.

If you plan to trade under a name that isn’t your legal name (as a sole trader) or your company’s exact name, you’ll generally need to register a business name. Understanding the branding steps alongside your structure can save rework later.

How To Find Or Check Your Numbers (ABN And ACN)

It’s common to misplace your details, particularly if you’ve had multiple ventures. Here’s how to locate them:

Finding Your ABN

• Use the public ABN search on the Australian Business Register to look up your ABN by business name, your own name (if a sole trader), or an ACN (for companies).
• Scan past invoices, tax returns and business portal records - your ABN often appears there.
• If you’re reactivating after a break, it’s worth confirming status and details are current. Here’s a quick primer on how to check if an ABN is active.

Finding Your ACN

• Your ACN sits on your ASIC certificate, ASIC correspondence and ASIC’s public company search. You can search by company name to retrieve it.
• Many companies include their ACN in email signatures and on websites to make it easy to find.

Lost Or Inactive ABN?

• If your ABN shows as cancelled, consider whether you should reapply or reactivate before trading again.
• ABNs don’t automatically “expire”, but they can be cancelled if you cease activity for a period - more on this in Does An ABN Expire?

What Legal Documents Will You Need?

Once you’ve sorted your structure and registrations, strong contracts and policies help you trade confidently and manage risk. The exact documents you need depend on your business model, but many early-stage businesses consider:

• Terms Of Trade (or Customer Agreement): Sets out pricing, scope, delivery, IP, liability and payment terms with your customers. Clear Terms Of Trade reduce disputes and late payments.
• Privacy Policy: Explains how you collect and handle personal information. It’s legally mandatory for some businesses (for example, APP entities, certain health providers or businesses with turnover above the threshold) and is a best-practice (and often expected) inclusion for most online businesses. Consider a tailored Privacy Policy if you collect customer data.
• Website or App Terms: Rules for visitors and users - helpful if you sell online or operate a platform.
• Employment or Contractor Agreements: If you’re hiring, use the correct Employment Contract or contractor agreement and have workplace policies in place for Fair Work compliance.
• Shareholders Agreement (for companies with co-founders/investors): Covers ownership, decision-making, vesting, exits and dispute processes - a Shareholders Agreement helps keep everyone aligned.
• NDAs and Supplier Agreements: Use non-disclosure agreements and robust supplier contracts when sharing confidential information or relying on third parties.

If you’re registering a company, also consider execution formalities - for example, how documents are signed under section 127 of the Corporations Act, board approvals and record-keeping. Getting these foundations right early makes growth much smoother.

Key Takeaways

• An ABN identifies your business for tax and trading; an ACN identifies a registered company under the Corporations Act - they serve different purposes.
• Sole traders and partnerships generally need an ABN; companies will have an ACN and should also obtain an ABN if they’re trading.
• Companies must display their ACN (or ABN, if used) on specific company documents and correspondence, while an ABN should appear on valid tax invoices.
• You can usually find your numbers via public ASIC and ABN searches; confirm that your ABN is active before resuming trade.
• Choosing the right structure impacts liability, governance and compliance; if you move to a company, plan for governance documents and director obligations.
• Protect your venture with tailored contracts and policies - Terms Of Trade, a Privacy Policy, hiring documents and (for companies) a Shareholders Agreement are common starting points.
• Tax and registration settings (like GST) depend on your situation - speak with your accountant if you’re unsure.

If you’d like a consultation on ABN vs ACN or setting up your Australian business the right way, you can reach us at 1800 730 617 or team@sprintlaw.com.au for a free, no-obligations chat.