ABN vs ACN vs ARBN: Differences and Which You Need
A practical reference for Australian businesses
An ABN identifies an enterprise to Australia’s tax and business systems, an ACN identifies an Australian company, and an ARBN identifies a registrable body such as a foreign company operating in Australia. A trading Australian company usually has both an ACN and an ABN.
ABN, ACN and ARBN compared
| Number | Issued by | Digits | Who uses it | Main purpose |
|---|---|---|---|---|
| ABN Australian Business Number | Australian Business Register | 11 | Sole traders, partnerships, companies, trusts and other enterprises | Tax, GST, invoicing and business dealings |
| ACN Australian Company Number | ASIC | 9 | Companies registered in Australia | Identifies the company under the Corporations Act |
| ARBN Australian Registered Body Number | ASIC | 9 | Registered foreign companies and registrable Australian bodies | Identifies a registrable body operating in Australia |
ABN — Australian Business Number
An ABN is an 11-digit identifier issued through the Australian Business Register, which is administered by the ATO. Most businesses obtain one so they can register for GST where required, issue compliant invoices and deal with customers and government agencies. If a supplier does not quote an ABN when required, the payer may need to withhold tax from the payment at the top rate.
An ABN identifies the enterprise rather than a particular legal structure. Sole traders, partnerships, companies and trusts can all hold an ABN.
ACN — Australian Company Number
An ACN is a 9-digit identifier issued by ASIC when an Australian company is registered. Only companies receive an ACN; sole traders and partnerships do not. Companies generally need to show it on public documents such as invoices, statements and contracts.
A company’s 11-digit ABN commonly contains its 9-digit ACN with two check digits added at the front. They identify different things, however: the ACN identifies the company, while the ABN identifies the company’s enterprise dealings with the tax and business systems.
ARBN — Australian Registered Body Number
An ARBN is a 9-digit identifier issued by ASIC to registrable bodies that are not Australian companies. The most common example is a foreign company registered to carry on business in Australia. Some registrable Australian bodies, including incorporated associations operating outside their home state or territory, may also receive one.
An ARBN does not replace an ABN. A registered foreign company may need an ARBN from ASIC and an ABN for its Australian enterprise and tax obligations.
Which number does each structure need?
- Sole trader: usually an ABN; never an ACN.
- Partnership: an ABN for the partnership; no ACN.
- Australian company: an ACN on registration and usually an ABN when it carries on an enterprise.
- Trust with a corporate trustee: the trustee company has an ACN; the trust may have its own ABN.
- Foreign company carrying on business in Australia: generally an ARBN and usually an ABN.
Common questions
Can I have an ABN without an ACN?
Yes. Sole traders, partnerships and trusts can hold an ABN but do not have an ACN because they are not Australian companies.
Can a company have an ACN without an ABN?
Yes, technically. An ACN is created when the company is registered, while an ABN relates to carrying on an enterprise. Most trading companies apply for both.
Is an ARBN the same as an ABN?
No. ASIC issues the ARBN to identify a registrable body. The Australian Business Register issues the ABN for enterprise and tax dealings. A foreign company may hold both.
Does it cost anything to apply?
Applying for an ABN through the official Australian Business Register is free. Company registration and ASIC annual review fees apply to companies, while foreign-company registration has its own ASIC fees. Check current amounts with the official agencies because fees are indexed.
Sources: Australian Business Register (ABN); ASIC (ACN and ARBN); ATO (ABN withholding and GST). Current as at 24 July 2026. General information, not legal or tax advice.
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