Australian Business Number

Detects Australian Business Numbers (ABNs), which are unique 11-digit identifiers issued by the Australian Business Register to entities carrying on a business in Australia. ABNs are commonly formatted as groups of 2-3-3-3 digits separated by spaces or hyphens. The ABN includes a check digit mechanism, but this pattern relies on format matching combined with corroborative evidence rather than algorithmic validation.

Type: regex
Engine: boost_regex
Confidence: medium
Confidence justification: Medium confidence because the 11-digit format is relatively common in financial and administrative contexts. While the 2-3-3-3 grouping is distinctive, the pattern can match other 11-digit sequences without algorithmic check digit validation. Corroborative evidence keywords such as "ABN" or "Australian business number" significantly increase detection accuracy.
Jurisdictions: au
Regulations: AML/CTF Act (Cth), NDB Scheme (Cth), Privacy Act 1988 (Cth)
Frameworks: ISO 27001
Data categories: financial, business-id
Scope: narrow
Risk rating: 5
Platform compatibility: Purview: Compatible, GCP DLP: Compatible, Macie: Compatible, Zscaler: Compatible, Palo Alto: Compatible, Netskope: Compatible

Pattern

\b\d{2}[\s-]?\d{3}[\s-]?\d{3}[\s-]?\d{3}\b

Corroborative evidence keywords

ABN, Australian business number, business number, A.B.N., australian business number, bank account, account number, account no, BSB, routing number, sort code, IBAN, SWIFT, BIC

Proximity: 300 characters

Should match

51 824 753 556 — Standard spaced format (2-3-3-3 grouping)
51-824-753-556 — Hyphen-separated format (2-3-3-3 grouping)
51824753556 — Continuous digits without separators

Should not match

1234567890 — Only 10 digits, one short of the required 11-digit ABN length
123 456 789 012 3 — 13 digits in a non-ABN grouping, exceeds the 11-digit ABN length

Known false positives

Sequences of 11 digits appearing in unrelated contexts such as tracking numbers, serial codes, or account references Mitigation: Require corroborative evidence keywords within the proximity window. Without keywords like 'ABN' or 'business number' nearby, suppress the match or lower the confidence score.