ACN vs ABN: What's the difference?

Confused about ABN vs ACN? You’re not alone. If you’re starting a business in Australia, it’s easy to mix them up. Although they might look similar, each serves its own purpose—and knowing the difference can save you time, money, and a lot of headaches.

This guide will break down what each number is, who needs it, and how to register, update, or cancel them. By the end, you’ll have a clear picture of which applies to your business—and why it matters.

What is an ABN?

An Australian Business Number (ABN) is a unique 11-digit identifier issued by the Australian Business Register (ABR) and operated by the Australian Taxation Office (ATO) [1].

It identifies your business to the government, other businesses, and the public, and you can use it for a variety of purposes—from registering for Goods and Services Tax (GST) to claiming business expenses as tax deductions, avoiding PAYG tax on payments you receive, and more.

What is an ACN?

An Australian Company Number (ACN) is a unique 9-digit identifier assigned by the Australian Securities and Investments Commission (ASIC) to every business registered as a company in Australia [2]. This means neither sole traders nor partnerships are entitled to an ACN.

Your ACN keeps ASIC in the loop on your company activities while also showing the public how your business is set up, and you need to display it in:

• All documents lodged with ASIC
• Invoices and statements of account
• Receipts (unless they're machine-produced)
• Orders for goods and services
• Business letterhead
• Official company notices
• Cheques, promissory notes, and bills of exchange

Key differences between an ABN and an ACN

In a nutshell:

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Who needs an ABN vs ACN?

Need for an ABN

Not everyone needs (or is entitled to) an ABN. If you meet any of the criteria below, you're required to apply:

• Your business's GST turnover is over $75,000, and so you need to register for GST
• You send invoices or quotes for work as a contractor
• You import or export goods for business purposes, or
• You need to register for other tax obligations, like PAYG withholding, FBT, or luxury car tax

Even if you’re not legally required to, you can still get an ABN—as long as you're running or starting an enterprise in Australia, making supplies connected with Australia's indirect tax zone, or registered under the Corporations Act [3].

The benefits? You can register for GST voluntarily, avoid the “no-ABN withholding” hit, simplify your tax and record-keeping, and prepare for scaling up without having to redo contracts, invoicing systems, and bank accounts later on.

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Keep in mind, though, that applying for an ABN, registering for GST, and claiming GST refunds when you’re not entitled to can lead to legal consequences. Before you get the ball rolling, make sure you're okay to do so.

Need for an ACN

All registered companies need an ACN—Pty Ltd and not-for-profit.

How to register for an ABN and an ACN

Registering for an ABN

• Check your eligibility
• Get the information you need—your TFN (for sole traders), details of your business structure, business name (if registered), contact details, and a description of your key business activities
• Apply online through the ABR website

You'll typically receive your ABN immediately or, if the ABR needs to review your application, in up to 20 days [4].

Registering for an ACN

• Make sure a company is the right structure for your business
• Choose and register (or reserve) a company name [5]
• Provide a registered office address and a principal place of business address [6]
• Decide how your company will be internally managed [7]
• Provide your company’s share structure and the number and type of shares issued
• Provide details for each proposed officeholder of your company
• Pay a registration fee (currently $503 or $611, depending on the type of company) [8]

Once your application is processed, your company will be registered and you'll receive an ACN.

How to find your ABN or ACN details

You can use the ATO's ABN Lookup to search for your ABN, and you can have a look at your tax invoice or any letters sent to you by the government—the 11-digit identifier should also be there.

You can use the same page to find your ACN or ASIC's Search ASIC Registers tool.

How to update your ABN or ACN

Updating an ABN

Keeping your ABN details accurate is important both for compliance and smooth business operations.

You should update your ABN whenever there are changes to your business name or trading name, business structure, contact details, business location or principal place of business, or GST registration status.

• Log in to the ABR online service
• Choose your ABN record and click “Update ABN details.”
• Make the necessary changes and confirm them

Most updates are processed immediately, but some may require ABR review.

Updating an ACN

Although your ACN will remain the same, the details linked to it have to be kept current with ASIC—or you risk missed notices, fines, or other compliance headaches.

These details include your registered office or principal place of business, officeholders, share structure or number of shares issued, and company rules or constitution.

• Log in to ASIC Connect
• Choose your company and the relevant update form
• Submit the form, and if needed, pay any associated fees

How to cancel your ABN or ACN

Cancelling an ABN

You should cancel your ABN if your business has been sold, closed down, changed business structures, or is no longer operating in or making supplies connected with Australia [9]. Here's how:

• Make sure you've met all your lodgement, reporting, and payment obligations—things like repaying GST credits or lodging PAYG withholding reports
• Log in to ABR online services
• Select your ABN record and click the “Cancel” option
• Follow the prompts to confirm your details and reason why you're cancelling

Cancelling an ACN

You can cancel your ACN—or deregister—through ASIC, as long as you meet all these criteria [10]:

• All company members agree
• The company isn't trading
• The company's assets are worth less than $1000
• The company doesn't have outstanding liabilities
• The company isn't involved in any legal proceedings
• The company has paid all fees and penalties payable to ASIC

Here's how:

• Make sure your company bank accounts are closed, any registered business names and licences are cancelled, and your final tax return has been lodged
• Use ASIC’s online service or fill out form 6010
• Pay the deregistration fee (currently $50)

ASIC will then process the request—in up to 2 weeks for paper applications or immediately for online applications—and confirm the cancellation.