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Australia ABN Lookup

ABN validity check (11-digit mod 89 algorithm). Public ABR lookup needs ABN Lookup API.

⚠ 2024-25 Australian tax-year figures. Estimates only — consult the ATO or a registered tax agent.

How to use Australia ABN Lookup

  1. Enter an 11-digit Australian Business Number.
  2. The tool checks it against the official ABN checksum algorithm (mod 89) to confirm it's structurally valid.

Limitations

  • This validates the checksum only — it confirms the number is well-formed, not that it's an active, currently registered business. For a live registry lookup, use the official ABN Lookup (ABR) service.

About this tool

Australia ABN Lookup is a single-purpose utility on instant.tw, a free toolbox of calculators, converters, generators, and quick lookups. Everything works in your browser — nothing is uploaded, nothing is stored on a server unless explicitly noted.

Category: Tax & Government — Australia. Browse more Tax & Government — Australia tools.