ABN, ACN and business name: three basics newcomers often confuse
Three numbers, three different jobs
An ABN, an ACN and a business name are three completely different things in terms of function and the body that issues them — but they are often used interchangeably, especially by people just starting a business.
Understanding all three helps you: fill in forms correctly, print the right thing on invoices and business documents, and avoid administrative errors that can cause complications later.
ABN — Australian Business Number
What an ABN is: An ABN is an 11-digit identifier for a business, issued by the Australian Business Register (ABR) — a part of the ATO. Any business or organisation operating in Australia can register for an ABN.
Who needs an ABN:
- You are selling goods or services in the course of running a business
- You need to issue valid invoices to customers
- You want to register for GST
- You want to register a business name
Who issues it: The ABR (Australian Business Register) — you register through abr.gov.au.
When to use an ABN: On every invoice, on your website (if you are a business), when registering for GST, when registering a business name, and when dealing with other businesses.
Important note: If you supply a service without an ABN, the purchaser is obliged to withhold part of the payment for the ATO. This is why many customers will ask for your ABN before they pay.
Both sole traders and companies have an ABN: An ABN on its own does not reveal your business structure. A sole trader has an ABN. A company also has its own ABN.
ACN — Australian Company Number
What an ACN is: An ACN is a 9-digit identifier for a company only (a company registered with ASIC). Not a sole trader, not a partnership — only a company has an ACN.
Who issues it: ASIC (Australian Securities and Investments Commission) — the ACN is issued automatically when you register a company with ASIC.
How a company’s ACN and ABN relate: When you register a company, you receive an ACN from ASIC. The company then automatically also has an ABN, and the ABN usually begins with the first two digits of the ACN with certain changes.
When to use an ACN: The ACN must appear on all of the company’s official documents — letterhead, invoices and legal documents.
In short: If you do not have a company, you do not have an ACN and you do not need to think about it.
Business name — your trading name
What a business name is: A business name (or “trading name”) is the name you use to trade if it differs from the entity’s legal name.
Real examples:
- If you are a sole trader named An Nguyen and you trade under the name “Hoa Mai Bakery” — “Hoa Mai Bakery” is the business name you need to register with ASIC.
- If your company is “ABC Pty Ltd” but you want to trade under the name “Saigon Pho” — “Saigon Pho” is the business name.
Who issues it: ASIC — you register through asic.gov.au.
When you need to register a business name:
- When you want to use a trading name different from your legal name (personal or company)
- When you want to use that name consistently and with a degree of protection
When you do not need to register a business name:
- If you are a sole trader trading entirely under your own personal name
Note: Registering a business name with ASIC does not create a trademark right. These are two completely different things. If you want to protect your brand name, you need to register it separately with IP Australia.
Common points of confusion
Confusing an ABN with an ACN: On an invoice, you only need an ABN. If you are a company, you also need an ACN. Do not write the ABN where an ACN is asked for, or vice versa.
Using someone else’s ABN: An ABN cannot be shared. Every business or entity has its own ABN. Some newcomers borrow a friend’s or relative’s ABN — this is against the law and has serious consequences for both parties.
Forgetting to update ABN details: If your address, business activity or structure changes, you are obliged to update your ABN details on the ABR.
Registering a business name but forgetting to renew it: A business name needs to be renewed periodically. ASIC will send a reminder, but the responsibility for maintaining it remains yours.
Thinking a registered business name means a registered trademark: It does not. Registering a business name only registers your right to use that name within Australia’s business system — it does not protect you from someone else using a similar name as a trademark.
A one-line summary
| ABN | ACN | Business Name | |
|---|---|---|---|
| For | Every business | Companies only | A trading name different from the legal name |
| Issuing body | ABR (ATO) | ASIC | ASIC |
| Mandatory? | Strongly recommended | Automatic with a company | Only if using a different name |
Next step: understand how your business structure affects your obligations in the guide on choosing a business structure in Australia, and get an overview of tax in the guide on tax and accounting for small business owners in Australia.