ABN vs ACN: What's the Difference? (2026 Guide)

ABN vs ACN: What's the Difference? (2026 Guide)

ABN vs ACN explained: what each number is, when you need them, the key differences in a simple table, and how to check if a business has both. Updated for 2026.

👤 QELab Team 📅 5/11/2026 ⏱️ 8 min read
abn vs acn abn acn australian business difference between abn and acn business registration

ABN vs ACN: What's the Difference? (2026 Guide)

If you're starting a business in Australia — or dealing with one — you'll encounter two important numbers: the ABN (Australian Business Number) and the ACN (Australian Company Number). They look similar, get confused constantly, and serve very different purposes.

This guide explains what each one is, when you need which, and how to check whether a business has both.

What Is an ABN?

An Australian Business Number (ABN) is an 11-digit identifier issued by the Australian Taxation Office (ATO) via the Australian Business Register (ABR). It's available to any entity carrying on a business in Australia:

  • Sole traders and freelancers

  • Partnerships

  • Trusts

  • Companies (Pty Ltd and public)

  • Government entities

  • Superannuation funds

You use your ABN on invoices, tax returns, BAS statements, and any business-to-business transaction. If you don't quote an ABN on an invoice, the paying entity must withhold 47% from your payment — which makes having one essentially mandatory for anyone doing business.

Key facts:

  • 11 digits, validated with a mod-89 checksum algorithm

  • Issued by the ATO / ABR


  • Required for GST registration (mandatory if turnover > $75K)

What Is an ACN?

An Australian Company Number (ACN) is a 9-digit identifier issued by ASIC (Australian Securities and Investments Commission) when you register a company. It's exclusive to:

  • Proprietary limited companies (Pty Ltd)

  • Public companies (Ltd)

  • Companies limited by guarantee

An ACN proves your company exists as a separate legal entity. It appears on all official company documents, ASIC filings, contracts, and the company register. You cannot open a company bank account or sign contracts as a company without one.

Key facts:

  • 9 digits, validated with a mod-10 checksum algorithm

  • Issued by ASIC

  • Costs $576 to register (2026 ASIC fee for online registration)

  • Only for registered companies — not sole traders, partnerships, or trusts

Key Differences: ABN vs ACN at a Glance


































































ABN ACN
Digits 11 9
Issued by ATO (via ABR) ASIC
Available to Any business entity Companies only
Purpose Tax identification & invoicing Company registration & legal identity
Cost Free $576 (2026)
Required for Invoicing, GST, tax Incorporating as Pty Ltd or public company
Appears on Invoices, BAS, tax returns Company documents, contracts, ASIC filings
Sole traders ✅ Yes ❌ No
Partnerships ✅ Yes ❌ No
Trusts ✅ Yes ❌ No
Companies ✅ Yes (also need ABN) ✅ Yes

The critical relationship: If you have an ACN, you also need an ABN. But if you have an ABN, you don't necessarily have an ACN. Companies get both; sole traders, partnerships, and trusts only get an ABN.

When Do You Need Each One?

You need an ABN if:

  • You're running any kind of business in Australia (any structure)

  • You're issuing invoices to clients or customers

  • Your turnover exceeds $75K (GST registration becomes mandatory)

  • You want to avoid the 47% PAYG withholding on payments to you

  • You're registering for a business name

  • You're contracting for government work

You need an ACN if:

  • You're incorporating as a Pty Ltd or public company

  • You want limited liability (personal assets protected from business debts)

  • You're seeking investment from venture capital or angel investors

  • You need to sign contracts as a separate legal entity

  • You're planning to issue shares or eventually IPO

  • You need the credibility of a registered company structure

You DON'T need an ACN if:

  • You're a sole trader or freelancer

  • You're operating as a partnership

  • You're a trustee of a business trust

  • You're a government entity or association

How to Check If a Business Has Both

Use QELab's ABN Lookup tool — enter any ABN or business name and the result card shows:

  • The ABN and its status (Active/Cancelled)

  • The ACN (if the entity is a registered company)

  • Entity type (which tells you whether an ACN should exist)

  • GST status, state, registration date, and trading names

If the entity type is "Australian Private Company" or "Australian Public Company", there will be an associated ACN. For sole traders, trusts, and partnerships, no ACN exists.

> 👉 Check any business now: Free ABN Lookup →

You can also verify an ACN directly on the ASIC company register — but QELab shows both ABN and ACN details in one result, which saves time.

Can a Sole Trader Have an ACN?

No. This is one of the most common questions. An ACN is exclusively for registered companies (Pty Ltd or public companies). If you're operating as a sole trader, you have an ABN but no ACN.

If you want an ACN, you need to incorporate — register a company with ASIC. Many sole traders eventually do this when:

  • Their income grows and they want asset protection (limited liability)

  • They want to bring on co-founders or investors

  • Tax structuring makes a company advantageous (consult your accountant)

  • They need the credibility of "Pty Ltd" for enterprise clients

When you incorporate, you can apply for your ACN and ABN at the same time through the ABR.

Frequently Asked Questions

Do I need both an ABN and an ACN?

If you're registering a company (Pty Ltd or public), yes — you need both. The ACN identifies your company with ASIC, and the ABN identifies it with the ATO for tax purposes. If you're a sole trader, partnership, or trust, you only need an ABN.

Can I find an ACN using an ABN?

Yes. Use QELab ABN Lookup — enter the ABN and the result card displays the associated ACN if the entity is a registered company.

Is an ABN the same as a tax file number (TFN)?

No. A TFN is for personal tax identification. An ABN is specifically for business transactions and identity. They're separate numbers for separate purposes, though they're both managed by the ATO.

How much does it cost to get an ABN and ACN?

An ABN is free to register. An ACN costs $576 (2026 ASIC registration fee for online applications). Both can be applied for simultaneously when incorporating a company.

What happens if I use the wrong number on a document?

Using an ACN where an ABN is required (or vice versa) can cause payment delays, incorrect withholding, and compliance issues. Always double-check which number is being requested. When in doubt, look it up.

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