verifyabn

What is an ABN (Australian business number)?

An ABN is "a unique 11-digit number that identifies your business or organisation to the government and community" (ABR: Applying for an ABN (opens in a new tab)). You need one to register for GST, to avoid tax being withheld from what businesses pay you, and to identify your business when ordering and invoicing (ATO: Business or company registrations (opens in a new tab)).

Updated . Checked against abr.gov.au, ato.gov.au and asic.gov.au the same day.

51 2 check digits. Worked out from the other 9 digits with the ABR's modulus 89 calculation (ABN Lookup: Format of the ABN (opens in a new tab)).

824 753 556 9-digit identifier. For a company, often its ACN (ASIC: Australian Company Number (ACN) (opens in a new tab)).

The ABR's own example ABN, 51 824 753 556, split the way the ABR describes it.

What an ABN does

The ATO says you need an ABN to (ATO: Business or company registrations (opens in a new tab)):

  • operate in the GST system, including claiming GST credits;
  • avoid pay as you go tax being withheld from payments you receive;
  • confirm your business identity to others when ordering and invoicing;
  • set up access to government online services for your business;
  • be endorsed as a deductible gift recipient or an income tax exempt charity.

If you're paying a supplier who doesn't quote an ABN and the payment is over $75 excluding GST, you generally withhold 47% (ATO: Withholding if ABN is not provided (opens in a new tab); ATO: Foreign resident PAYG withholding (top rate of tax: 47%) (opens in a new tab)). That is why paying businesses check ABNs: you can check one here.

What anyone can see about an ABN

The ABR splits an ABN's details into public and non-public (ABR: Your ABN details on the ABR (opens in a new tab)):

Public on ABN LookupNot public on ABN Lookup
The ABN, its status and datesStreet address of the business
Entity legal name and entity typePhone numbers and authorised contacts
GST registration and datesAssociates (partners, directors, trustees)
Registered business namesIndustry code (ANZSIC)
State and postcode of the main business addressMailing address for notices
ACN or ARBN, where there is oneLatitude and longitude of locations
DGR, charity (ACNC) and tax concession status, where they apply

A business can ask for its name, entity type and postcode to be withheld if publishing them could put someone at risk (ABR: Request non-disclosure of ABN details (opens in a new tab)). Trading names collected before May 2012 are shown only as history with no legal status (ABN Lookup: Glossary (opens in a new tab)).

ABN, ACN, TFN and business name

Number or nameWhat it isPublic?
ABN11 digits, for any type of business, including sole traders and partnerships; issued by the ATO (ASIC: Australian Company Number (ACN) (opens in a new tab))Yes, on ABN Lookup (ABR: Your ABN details on the ABR (opens in a new tab))
ACN9 digits, identifies a company; issued by ASIC when the company is registered (ASIC: Australian Company Number (ACN) (opens in a new tab))Yes, on ASIC's company register and on the company's ABN record (ASIC: Australian Company Number (ACN) (opens in a new tab); ABR: Your ABN details on the ABR (opens in a new tab))
TFNYour tax file number. The ABR asks for it when you apply for an ABN (ABR: What you need for your ABN application (opens in a new tab))No; it isn't among the details ABN Lookup shows (ABR: Your ABN details on the ABR (opens in a new tab))
Business nameThe name a business trades under when it isn't the owner's own name; registered with ASIC, and you need an ABN, or its application reference number, first (ASIC: Register a business name (opens in a new tab); ASIC: How to register a business name with ASIC (opens in a new tab))Yes, on ASIC's business names register (ASIC: Business names register (opens in a new tab))

Most companies have both an ABN and an ACN, and the ABN is often the ACN with 2 extra digits in front. When it is, the company can show its ABN where it would otherwise show its ACN (ASIC: Australian Company Number (ACN) (opens in a new tab)). See ABN vs ACN for the full difference, or ACN lookup.

How an ABN is built

An ABN is "a 9 digit identifier with two leading check digits", derived with a modulus 89 calculation (ABN Lookup: Format of the ABN (opens in a new tab)). The ATO adds that an ABN has 11 digits, no letters, and never starts with 0 (ATO: Checking an ABN (opens in a new tab)). Because of the check digits, most typos produce a number that can't be an ABN, which the checker on the home page explains digit by digit.

Active or cancelled

An ABN has one of two statuses. ABN Lookup's glossary says a cancelled ABN "means the business has ceased trading" (ABN Lookup: Glossary (opens in a new tab)). Businesses cancel their own ABNs when they sell or close (ABR: Cancel your ABN (opens in a new tab)), and the ABR cancels ABNs it finds inactive, or when ASIC notifies it that a company has been deregistered (ABR: ABR integrity (ABN cancellation program) (opens in a new tab)). Cancelling an ABN also cancels its GST registration (ABR: Cancel your ABN (opens in a new tab)).

ABNs and GST

Registering for an ABN doesn't register you for GST. You must register for GST once your GST turnover reaches $75,000 ($150,000 for non-profits), and the ATO says to check each month whether you've reached the threshold or are likely to exceed it. Some cases, such as taxi and ride-sourcing driving, need registration whatever your turnover: the full list is on the how to get an ABN page. You need an ABN before you can register (ATO: Registering for GST (opens in a new tab)). The ABN record shows whether, and from when, a business is registered for GST.

Questions people ask

Is an ABN the same as a TFN?

No. A tax file number is your own tax number and isn't published. An ABN identifies a business to the government and the community (ABR: Applying for an ABN (opens in a new tab)), and most of its details are public on ABN Lookup (ABR: Your ABN details on the ABR (opens in a new tab)). A sole trader can have both: the ABR asks for your TFN when you apply for an ABN (ABR: What you need for your ABN application (opens in a new tab)).

Does everyone need an ABN?

No. You're entitled to an ABN if you're carrying on or starting an enterprise in Australia, making supplies connected with Australia's indirect tax zone, or a Corporations Act company. You're not entitled to one for work you do as an employee, even when an employer calls it contracting (ABR: ABN entitlement (opens in a new tab)).

Do I need an ABN if I earn under $75,000?

Possibly. $75,000 is the GST threshold, not an ABN threshold, and the ABR says you may still need an ABN below it (ABR: ABN important facts (opens in a new tab)). What matters is whether you're carrying on or starting an enterprise (ABR: ABN entitlement (opens in a new tab)).

Are all ABNs 11 digits?

Yes, every ABN has 11 digits. The ATO adds that branches of some entities also have a separate 3-digit GST or PAYG registration number for tax purposes (ATO: Checking an ABN (opens in a new tab)).

Can I find my own ABN?

Yes. Search your name or business name on the lookup here or on ABN Lookup. You can also ask the ABR for a free extract of your own ABN details (ABR: Paper copies of ABN details (opens in a new tab)).

Does an ABN expire?

No. "Your ABN is for life", but the ABR also says "you are only entitled to an ABN while you're running an enterprise" and checks periodically (ABR: ABN important facts (opens in a new tab)). If it's cancelled, the status on the register changes to Cancelled.

Sources

Every rule on this page comes from the official pages listed here. Each was read on the date shown, and the Updated date at the top is when this page was last checked against them.

  1. ABR: Paper copies of ABN details (opens in a new tab) Read 30 September 2026.
  2. ASIC: Business names register (opens in a new tab) Read 30 September 2026.
  3. ABR: Applying for an ABN (opens in a new tab) Read 30 September 2026, page updated 11 June 2026.
  4. ABR: Your ABN details on the ABR (opens in a new tab) Read 30 September 2026, page updated 5 August 2024.
  5. ABR: ABN entitlement (opens in a new tab) Read 30 September 2026, page updated 29 February 2024.
  6. ABR: ABN important facts (opens in a new tab) Read 30 September 2026, page updated 17 June 2022.
  7. ABR: What you need for your ABN application (opens in a new tab) Read 30 September 2026, page updated 14 November 2022.
  8. ABR: Request non-disclosure of ABN details (opens in a new tab) Read 30 September 2026.
  9. ABR: Cancel your ABN (opens in a new tab) Read 30 September 2026, page updated 26 August 2026.
  10. ABR: ABR integrity (ABN cancellation program) (opens in a new tab) Read 30 September 2026.
  11. ABN Lookup: Format of the ABN (opens in a new tab) Read 30 September 2026.
  12. ABN Lookup: Glossary (opens in a new tab) Read 30 September 2026.
  13. ATO: Business or company registrations (opens in a new tab) Read 30 September 2026, page updated 13 November 2024, QC31785.
  14. ATO: Checking an ABN (opens in a new tab) Read 30 September 2026, page updated 11 June 2025, QC51686.
  15. ATO: Withholding if ABN is not provided (opens in a new tab) Read 30 September 2026, page updated 11 June 2025, QC51682.
  16. ATO: Foreign resident PAYG withholding (top rate of tax: 47%) (opens in a new tab) Read 30 September 2026, page updated 3 June 2026, QC18618.
  17. ATO: Registering for GST (opens in a new tab) Read 30 September 2026, page updated 14 September 2026.
  18. ASIC: Australian Company Number (ACN) (opens in a new tab) Read 30 September 2026.
  19. ASIC: Register a business name (opens in a new tab) Read 30 September 2026.
  20. ASIC: How to register a business name with ASIC (opens in a new tab) Read 30 September 2026.