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Australian ABN Format & Checksum Checker

Check an 11-digit ABN for typing errors using the official modulus-89 checksum.

Tool inputs stay in your browser · optional AI search sends your query

Good to know: A passing checksum only confirms the number’s mathematical format. It does not confirm registration, active status, GST registration, business identity, or trustworthiness. Use official ABN Lookup before relying on a business detail. No registry request is made by this tool.

How to use it (step by step)

  1. 1Enter the 11-digit ABN. Spaces are allowed; letters and punctuation are not.
  2. 2Read the format/checksum result. A pass is not proof of a real or trustworthy business.
  3. 3Open official ABN Lookup below to verify the entity, status, and GST details independently.

Words to know

ABN
An Australian Business Number, normally displayed as 2 digits followed by three groups of 3.
Checksum
A mathematical typing-error check; it is not a live registration search.

Explore tools for Australia, the US & Europe →

Sources & methods

References checked November 11, 2026. Read each tool’s scope and assumptions before relying on its result.

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