# abn

CEFR C1 · Noun

Source: https://englishreference.com/word/abn
Updated: 2026-05-18

## Definition

Stands for Australian Business Number. A unique nine-digit number that identifies a business in Australia. It is required for most official business activities.

For teachers: Abbreviation for Australian Business Number. A nine-digit identifier issued by the Australian government to legal entities and sole traders for tax and business registration purposes.

## Examples

- You must include your ABN on every invoice.
- The accountant reminded the small business owner to register for an ABN before starting to sell goods online.
- Failure to display a valid ABN on a commercial invoice can result in the recipient being unable to claim a tax deduction for the purchase.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.