ABN vs ACN: what's the difference?
An ABN (Australian Business Number) is an 11-digit number from the ATO that identifies any type of business. An ACN is a 9-digit number from ASIC that identifies a company. Most companies have both (ASIC: Australian Company Number (ACN) (opens in a new tab)).
Updated . Checked against asic.gov.au, abr.gov.au, ato.gov.au and business.gov.au the same day.
The short version
- ABN
- 11 digits. Identifies any type of business. Issued by the ATO
- ACN
- 9 digits. Identifies a company. Issued by ASIC when the company is registered
- Sole trader, partnership or trust
- An ABN, if you're carrying on an enterprise. No ACN, because you don't register a company
- Company
- An ACN first. Most companies then get an ABN too
- Same number?
- No, but a company's ABN is often its ACN with 2 extra digits in front
What is an ACN?
ACN stands for Australian Company Number. ASIC's definition: "An ACN is a unique 9-digit number that identifies a company. ASIC issues every company with an ACN when it is registered." (ASIC: Australian Company Number (ACN) (opens in a new tab))
The last digit is a check digit, used to spot typing mistakes (how the check works). To get an ACN, you register a company: how to get an ACN walks through it.
If a company doesn't choose a name, its name is its ACN plus its legal status. ASIC's example is "ACN 123 456 789 Pty Ltd" (ASIC: Register a company (opens in a new tab)).
For what an ABN is and what it does, see What is an ABN?
ABN and ACN side by side
| Detail | ABN | ACN |
|---|---|---|
| Digits | 11 | 9 |
| Issued by | The ATO (ASIC: Australian Company Number (ACN) (opens in a new tab)) | ASIC (ASIC: Australian Company Number (ACN) (opens in a new tab)) |
| Who has one | Businesses and organisations entitled to one, including sole traders and partnerships (ASIC: Australian Company Number (ACN) (opens in a new tab); ABR: ABN entitlement (opens in a new tab)) | Companies (ASIC: Australian Company Number (ACN) (opens in a new tab)) |
| What it does | Identifies your business to the government and community. You need it to operate in the GST system and, generally, to avoid tax being withheld from payments over $75 (excluding GST) that you receive (ABR: Applying for an ABN (opens in a new tab); ATO: Business or company registrations (opens in a new tab); ATO: Withholding if ABN is not provided (opens in a new tab)) | Identifies a company on ASIC's register. Companies must show it on certain documents (ASIC: Australian Company Number (ACN) (opens in a new tab)) |
| How you get one | Apply to the Australian Business Register. It's free (business.gov.au: Register for an Australian Business Number (opens in a new tab)) | Register a company with ASIC. The fee is $636 for a company with a share capital and $524 for one without, as listed on 30 September 2026 (ASIC: Schedules of corporations fees (opens in a new tab)) |
| Where it's public | ABN Lookup (ABR: Your ABN details on the ABR (opens in a new tab)) | ABN Lookup, if the company has an ABN, and ASIC's company register (ABR: Your ABN details on the ABR (opens in a new tab); ASIC: Australian Company Number (ACN) (opens in a new tab)) |
| ASIC's illustration | 36 123 456 789 | 123 456 789 |
ASIC says a company's ABN is often its ACN with 2 extra digits in front. When it is, the company can show the ABN where it would have to show the ACN (ASIC: Australian Company Number (ACN) (opens in a new tab)).
Which one do you need?
It depends on how the business is set up.
- Sole trader. You're entitled to an ABN when you carry on, or start, an enterprise (ABR: Sole trader (opens in a new tab)). You don't register a company, so you don't get an ACN (ASIC: Register a company (opens in a new tab)).
- Partnership or trust. The same applies. These structures don't need to register as a company (ASIC: Register a company (opens in a new tab)), and they can have an ABN if they carry on an enterprise (ABR: ABN entitlement (opens in a new tab)).
- Company. You get an ACN when ASIC registers the company, and you need it before you can get the ABN and tax registrations (ATO: Business or company registrations (opens in a new tab)). A company registered with ASIC is entitled to an ABN (ABR: ABN entitlement (opens in a new tab)).
The steps are in how to get an ABN, which is free, and how to get an ACN. If you'll trade under a name that isn't your own or your company's, you may also need to register a business name (ASIC: Register a business name (opens in a new tab)). Check whether a business name is available.
Which number goes on an invoice?
A company must show its name and either its ACN or an ABN that contains the ACN on the first page of documents such as invoices and statements of account (ASIC: Australian Company Number (ACN) (opens in a new tab)). A company can use its ABN in place of its ACN only when the ABN is its ACN with 2 extra digits in front. If it isn't, the ACN must appear too (ASIC: Australian Company Number (ACN) (opens in a new tab)).
For GST, the ATO says a tax invoice must show the seller's ABN (ATO: Tax invoices (opens in a new tab)). A company that is registered for GST and whose ABN is its ACN with 2 extra digits in front can cover both rules with one number.
If you're the one paying, the ATO's rule on withholding turns on whether the supplier quotes an ABN (ATO: Withholding if ABN is not provided (opens in a new tab)). An ACN on its own isn't an ABN. Look the ACN up to see whether the company has an ABN and, if so, whether it is active.
Look up a company
Type an ACN, an ABN or a company name. The result is the ABN record of the entity you searched for, if the register has one, and a company's record includes its ACN (ABR: Your ABN details on the ABR (opens in a new tab)). It's free, and there's nothing to sign up for.
The ABN record doesn't show a company's directors or whether ASIC still has it registered. For those, see what an ABN record can't tell you about a company.
Questions people ask
What does ACN stand for?
Australian Company Number. It is the 9-digit number that identifies a company, and ASIC issues it when the company is registered (ASIC: Australian Company Number (ACN) (opens in a new tab)). To see the record behind one, use the ACN lookup.
Can I have an ABN without an ACN?
Yes, if you aren't a company. Sole traders, partnerships and trusts don't need to register as a company (ASIC: Register a company (opens in a new tab)), and you're entitled to an ABN if you're carrying on or starting an enterprise (ABR: ABN entitlement (opens in a new tab)). A company is different: it gets its ACN first, and the ATO says it needs the ACN before it can get its ABN and tax registrations (ATO: Business or company registrations (opens in a new tab)).
Does a company need an ABN as well as an ACN?
Not always, but most have both (ASIC: Australian Company Number (ACN) (opens in a new tab)). A company registered with ASIC is entitled to an ABN (ABR: ABN entitlement (opens in a new tab)). You need an ABN to operate in the GST system and, generally, to avoid tax being withheld from payments over $75 (excluding GST) that you receive (ATO: Business or company registrations (opens in a new tab); ATO: Withholding if ABN is not provided (opens in a new tab)).
Are the ABN and ACN the same number?
No. The ABN has 11 digits and the ACN has 9. But a company's ABN is often its ACN with 2 extra digits in front. ASIC illustrates this with ACN 123 456 789 and ABN 36 123 456 789 (ASIC: Australian Company Number (ACN) (opens in a new tab)). These are illustrative: neither passes its check digit test.
Can I find a company's ABN from its ACN?
Yes. If an entity with an ABN has an ACN, you can search ABN Lookup using the ACN (ABN Lookup: Glossary (opens in a new tab)). The ACN lookup here does the same and shows the ABN record.
Is a company's ACN public?
Yes. The ACN is among the details ABN Lookup shows for an entity that has one (ABR: Your ABN details on the ABR (opens in a new tab)), and you can search for an ACN on ASIC's company register, where some information is free and some is paid (ASIC: Australian Company Number (ACN) (opens in a new tab)).
Sources
Every rule on this page comes from the official pages listed here. Each was read on the date shown, and the Updated date at the top is when this page was last checked against them.
- ASIC: Australian Company Number (ACN) (opens in a new tab) Read 30 September 2026.
- ASIC: Register a company (opens in a new tab) Read 30 September 2026.
- ASIC: Register a business name (opens in a new tab) Read 30 September 2026.
- ASIC: Schedules of corporations fees (opens in a new tab) Read 30 September 2026, fees from 1 July 2026.
- ATO: Business or company registrations (opens in a new tab) Read 30 September 2026, page updated 13 November 2024, QC31785.
- ATO: Tax invoices (opens in a new tab) Read 30 September 2026, page updated 18 September 2026.
- ATO: Withholding if ABN is not provided (opens in a new tab) Read 30 September 2026, page updated 11 June 2025, QC51682.
- ABR: ABN entitlement (opens in a new tab) Read 30 September 2026, page updated 29 February 2024.
- ABR: Sole trader (opens in a new tab) Read 30 September 2026, page updated 14 November 2022.
- ABR: Applying for an ABN (opens in a new tab) Read 30 September 2026, page updated 11 June 2026.
- ABR: Your ABN details on the ABR (opens in a new tab) Read 30 September 2026, page updated 5 August 2024.
- ABN Lookup: Glossary (opens in a new tab) Read 30 September 2026.
- business.gov.au: Register for an Australian Business Number (opens in a new tab) Read 30 September 2026.