Compliance 14 April 2026

ABN, ACN and business setup – what you actually need

By SBI Editorial Team

Once you’ve decided on your business structure, the next step is to register it properly.

This is what makes your business official.

ABN — your business identifier

An ABN (Australian Business Number) is required for almost all businesses in Australia. It’s an 11-digit number that identifies your business when dealing with:

clients
suppliers
the ATO

You’ll use your ABN to issue invoices, receive payments, and register for other obligations like GST.

For most people, this is the first step in setting up a business. If you’re operating as a sole trader, an ABN is usually all you need to get started.

ACN — for companies only

If you’re setting up a company, you’ll also receive an ACN (Australian Company Number). This is a 9-digit number issued when your company is registered.

Unlike an ABN, the ACN is specifically used to identify your company as a separate legal entity.

In practice, a company will have both:

an ACN (for company registration and legal identification)
an ABN (for tax and business activities)

How this applies to your structure

What you need depends on how your business is set up.

Sole trader — you will typically only need an ABN.
Company — you will have both an ACN and an ABN.

Business name registration

Once you have your ABN, you may also need to register a business name — unless you are operating under your own personal name as a sole trader.

Check that your chosen name is available before registering. It is also worth checking whether the matching domain name is available if you plan to have an online presence.

Keeping your details updated

Once registered, it is important to keep your ABN details current with the Australian Business Register (ABR).

This includes updating any changes to your business structure, address, or activities. Outdated details can cause issues with the ATO and with clients who verify your ABN online.

What comes next

Once your business is registered, the next step is understanding your tax obligations — including GST, PAYG, and superannuation.