ABN vs ACN are both business identifiers in Australia, but they do very different jobs: an ABN identifies a business for tax and government dealings, while an ACN identifies a registered company for legal and regulatory purposes. Most small businesses only need an ABN, but if you register as a company you must have both an ACN and an ABN.
What is an ABN?
An Australian Business Number (ABN) is an 11‑digit identifier issued to entities registered in the Australian Business Register (ABR). It lets you deal with the ATO and other government agencies using a single ID and is used on invoices, tax and other business documents.
Key points about an ABN:
- Issued by the Australian Taxation Office (ATO) via the Australian Business Register.
- Available to many entity types: sole traders, partnerships, companies, trusts and non‑residents carrying on an enterprise in Australia.
- Must be used when dealing with government (e.g. GST, PAYG) and is commonly displayed on invoices and websites.
- Has 11 digits: two check digits followed by a 9‑digit identifier.
The ABR’s ABN basics FAQ explains what an ABN is, who can get one and its format, while the Business Registration Service page on selecting registrations outlines when you might need one when starting a business.
What is an ACN?
An Australian Company Number (ACN) is a 9‑digit identifier issued to every company registered with ASIC under the Corporations Act. It is used to identify and monitor companies and must appear on many of their public and legal documents.
Key points about an ACN:
- Issued automatically by ASIC when you register a company.
- Only companies get an ACN – sole traders, partnerships and trusts that aren’t companies do not.
- A 9‑digit number, usually printed in three groups of three (e.g. ACN 123 456 789).
- Must be shown on many company documents: ASIC forms, invoices, receipts, statements of account, orders for goods and services, public documents and legal correspondence.
ASIC’s page on the Australian Company Number (ACN) clearly sets out what an ACN is and where it needs to appear, and AON’s explainer on what is an ACN gives small‑business‑friendly examples of ACN usage.
ABN vs ACN: the core differences
At a high level, the ABN identifies your business for tax and government, while the ACN identifies your company for legal and regulatory purposes.
Here is a concise comparison.
| Feature | ABN (Australian Business Number) | ACN (Australian Company Number) |
|---|---|---|
| What it identifies | A business or enterprise (any eligible entity). | A registered company under the Corporations Act. |
| Who needs it | Any entity carrying on an enterprise (sole trader, partnership, trust, company, some non‑residents). | Companies only; required when you register with ASIC. |
| Issuing authority | Australian Taxation Office via the Australian Business Register (ABR). | ASIC (Australian Securities and Investments Commission). |
| Number format | 11 digits (2 check digits + 9‑digit identifier). | 9 digits (usually grouped as xxx xxx xxx). |
| Main purpose | Tax, invoicing, government dealings (GST, PAYG, ABN Lookup, etc.). | Company identification, legal recognition, regulatory monitoring. |
| Documents used on | Invoices, tax returns, BAS, quotes and general business communications. | ASIC forms, public documents, invoices, receipts, letterheads and legal notices for companies. |
| Relationship | Most businesses need an ABN whether or not they are companies. | Every company must have an ACN; most companies also have an ABN. |
LawPath’s 2025 update on the difference between an ABN and ACN and Australian Accountants’ article on ABN vs ACN: key differences both give accessible breakdowns of these points.
Do you need an ABN, an ACN, or both?
What you need depends on your business structure and how you plan to operate.
- Sole traders, partnerships and many trusts:
- Usually need an ABN to invoice clients, register for GST and interact with government, but do not get an ACN.
- Companies (Pty Ltd, public companies):
- Must have an ACN issued by ASIC when they register.
- Generally also apply for an ABN, because companies still need to deal with the ATO, register for GST and issue tax invoices.
- Foreign entities doing business in Australia:
Wise’s overview on ABN vs ACN and Company Setup Australia’s ABN vs ACN guide both use simple scenarios to show when each number is required.
How to get an ABN
Applying for an ABN is done online and is free, but you must be entitled to one (for example, genuinely carrying on a business or enterprise).
Basic steps:
- Confirm you’re entitled – Check whether you are carrying on or starting an enterprise in Australia or making sales connected with Australia.
- Gather information – Business structure details, TFN, business activities, trading name and location.
- Apply via the ABR / Business Registration Service – Use the government Business Registration Service or the ABR site to lodge your ABN application.
- Wait for approval – Most applications are processed instantly; if more information is needed, it can take longer.
The ABR’s glossary and FAQs explain ABN format and status, while the ATO’s page on ABN for non‑residents covers overseas entities.
How to get an ACN
You cannot apply for an ACN separately; you get one when you register a company with ASIC.
Basic steps:
- Choose a company structure and name – Decide, for example, whether to set up a proprietary limited (Pty Ltd) company.
- Register the company with ASIC – During registration, ASIC allocates your 9‑digit ACN.
- Use your ACN on company documents – Once registered, you must display your full company name and ACN (or in many cases your ABN if you have one) on key documents.
ASIC’s ACN information page lists exactly which documents must show an ACN, and Remitly’s explainer on ACN numbers in Australia summarises the process in plain language.
Where you must display ABN and ACN
Using your numbers correctly is a key part of compliance.
ABN usage:
- Commonly displayed on tax invoices and adjustment notes.
- Often shown on websites, email signatures and marketing materials to signal you are a registered business.
- Used on BAS statements, tax returns and when interacting with government agencies.
ACN usage (for companies):
- Must appear on many public documents: ASIC forms, notices, statements issued to shareholders or creditors.
- Required on invoices, receipts (except some machine‑produced ones), orders for goods and services, business letterheads and many legal documents.
- Companies can show their ABN instead of ACN in some cases, but if the ABN includes the ACN digits (most do), you still meet the requirement.
Australian Accountants’ article on ABN vs ACN: key differences and Company Setup Australia’s ABN vs ACN guide both outline the document rules in practical terms.
Why ABN vs ACN matters for business owners
Understanding ABN vs ACN is more than just paperwork; it affects how you structure and present your business.
Practical implications:
- Credibility and perception – Having an ACN (and therefore a company) can signal that your business is a separate legal entity, which some clients and suppliers may prefer for larger contracts.
- Legal protection – Companies with an ACN are separate legal entities; directors usually aren’t personally liable for company debts, unlike sole traders or partners who only have an ABN.
- Tax and admin – An ABN is essential for tax, GST and PAYG purposes; without one, payers may withhold tax at the top marginal rate from payments to you.
- Expansion – As you grow, you might move from operating solely under an ABN (as a sole trader) to registering a company and gaining an ACN while keeping your ABN for tax and invoicing.
Articles by LegalVision and LawPath on the difference between an ABN and ACN and 2025 ABN vs ACN update are good external reads for small‑business owners weighing up structure and compliance.