ABN vs ACN Explained
If you have set up — or are thinking of setting up — a business in Australia, you have almost certainly come across two acronyms that look alike and get confused constantly: ABN and ACN.
They are not the same thing. They are issued by different regulators, they do different jobs, and whether you need one, the other, or both depends on how you structure your business.
This guide explains what each number is, who needs it, how to get it, and how the two fit together.
The Short Answer
- An ABN (Australian Business Number) is an 11-digit identifier issued by the Australian Taxation Office. It identifies your business to the ATO, other businesses, and the public. Every business that trades in Australia needs one.
- An ACN (Australian Company Number) is a 9-digit identifier issued by ASIC when a company is registered. Only companies have an ACN.
Put simply: every company has an ACN and an ABN. Every sole trader, partnership, and trust has an ABN but no ACN.
What Is an ABN?
The Australian Business Number is your business's identifier for tax and trading purposes. It was introduced with the GST in 2000 to give every business a single number that could be used across dealings with the ATO, other businesses, and government agencies.
Your ABN is what you put on:
- Invoices and quotes
- Contracts and agreements
- Your website and marketing materials
- GST returns and BAS statements
- Payments received from other businesses (who would otherwise have to withhold tax at 47%)
You must have an ABN if you are carrying on an enterprise in Australia. Trading without one — where you should have one — exposes you to PAYG withholding on every business-to-business payment you receive.
Who Issues ABNs?
The Australian Taxation Office, through the Australian Business Register. Applications are free and can be made online at abr.gov.au.
Who Can Get an ABN?
Any entity carrying on (or intending to carry on) an enterprise. This includes:
- Sole traders
- Partnerships
- Companies
- Trusts (through their trustee)
- Not-for-profit organisations and charities
What Is an ACN?
The Australian Company Number is a 9-digit identifier assigned by ASIC (the Australian Securities and Investments Commission) to every company registered under the Corporations Act 2001 (Cth).
An ACN identifies the company as a legal entity. It is separate from the ABN, which identifies the company as a business.
Companies must display their ACN (or ABN, which contains the ACN) on:
- Every public document issued by the company
- Company invoices, letterheads and negotiable instruments
- The company's website and email footers (as a matter of best practice)
- Official notices lodged with ASIC
Who Gets an ACN?
Only companies. If you register a proprietary limited company (Pty Ltd), a public company, or a foreign company doing business in Australia, ASIC will issue you an ACN. Sole traders, partnerships, and trusts do not get an ACN.
The Relationship Between ABN and ACN
For a company, the two numbers are mathematically linked. Your ABN is your ACN with two extra "check" digits added to the front:
ABN = XX + ACN
So a company with ACN 123 456 789 will have an ABN like 12 123 456 789. You cannot choose the two extra digits — the ATO calculates them.
ABN vs ACN: A Side-by-Side Comparison
| ABN | ACN | |
|---|---|---|
| Full name | Australian Business Number | Australian Company Number |
| Digits | 11 | 9 |
| Issued by | ATO / ABR | ASIC |
| Identifies | The business | The company as a legal entity |
| Who needs one | Every business carrying on an enterprise | Only registered companies |
| Cost to obtain | Free | ASIC registration fee (currently a few hundred dollars) |
| Public register | ABN Lookup | ASIC company register |
| Required on invoices | Yes | Yes (for companies) |
Which Do You Need?
If you are a sole trader
You need an ABN. You do not need an ACN — there is no company to register.
If you are running a partnership
The partnership needs its own ABN. No ACN — a partnership is not a company.
If you are trading through a trust
The trustee applies for an ABN on behalf of the trust. If the trustee is a company (a "corporate trustee"), that company will have its own ACN — but the trust itself does not.
If you are running a company
You need both. ASIC issues the ACN when the company is registered. The company then applies to the ATO for an ABN so it can trade, invoice, and register for GST.
How to Get an ABN
- Go to abr.gov.au.
- Confirm you are entitled — you must be carrying on, or intending to carry on, an enterprise in Australia.
- Provide your entity details (sole trader name, partnership, trust, or company).
- Provide a TFN for each associate.
- Submit. If your details match ATO records, the ABN issues instantly.
There is no fee. Be wary of third-party sites charging for ABN registration — the ATO does not charge.
How to Get an ACN
- Choose and reserve a company name (or use the ACN as the name).
- Choose your company type — most trading businesses use a proprietary limited (Pty Ltd) company.
- Decide on directors, shareholders and share structure.
- Register with ASIC, either directly or through a lawyer, accountant, or online incorporation service.
- ASIC issues the ACN and a Certificate of Registration, usually within minutes.
You then apply for the ABN separately.
Common Mistakes
- Using an ABN when you should be using an ACN on formal company documents. A company must display its full identifier on public documents.
- Registering an ABN for something that is not really a business — a hobby, an investment, or a one-off transaction. The ATO can (and does) cancel ABNs that are not being used for genuine enterprise.
- Failing to update ABN details when you change address, structure or activities. Details must be kept current.
- Trading through a company but issuing invoices in a personal name. This creates confusion about who the counterparty actually is and can undermine the liability protection a company is meant to provide.
Frequently Asked Questions
Do I need both an ABN and an ACN?
Only if you run your business through a company. A company gets an ACN when it is registered with ASIC, and then applies for an ABN to trade. Sole traders, partnerships, and trusts do not have an ACN — they only need an ABN.
Is an ABN the same as being registered for GST?
No. An ABN is your business identifier. GST registration is separate and is only required once your annual turnover reaches $75,000 (or $150,000 for non-profits). You can hold an ABN without being registered for GST.
Can I use my ABN as my ACN?
Not directly. But every Australian company's ABN is built from its 9-digit ACN with two extra digits at the front. So if you know a company's ACN, you effectively know part of its ABN.
How long does it take to get an ABN or ACN?
An ACN is usually issued within minutes when you register a company through ASIC or an online formation service. An ABN application through the Australian Business Register is typically instant if your details match ATO records, or can take up to 28 days if further review is required.
Is my ABN or ACN public information?
Yes. Both are searchable on public registers — the Australian Business Register (ABN Lookup) and ASIC's company register. This is by design: they exist so customers, suppliers and regulators can verify who they are dealing with.
This article is general information and does not constitute legal advice. Envision Legal advises Australian businesses on choosing the right business structure, setting up companies and trusts, and ensuring day-to-day operations comply with tax and corporate law.
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