U.S. Alien Registration Number (A-Number)

Detects USCIS Alien Registration Numbers (A-Numbers). An A-Number is the unique identifier the Department of Homeland Security assigns to a noncitizen: the letter "A" followed by 7-9 digits, written compactly (A012345678) or grouped (A-123-456-789). A-Numbers appear on Green Cards, EADs, immigration court records, and Form I-9 / E-Verify data held by virtually every U.S. employer.

Type

regex

Engine

universal

Confidence

high

Confidence justification

High confidence: the mandatory "A" prefix plus a fixed 8-9 digit body and the optional grouping structure make this distinctive. Corroborative USCIS/immigration keywords are recommended because an "A" followed by digits can appear in unrelated reference codes.

Jurisdictions

us

Regulations

State Breach Laws (US), CCPA/CPRA, FTC Act s5

Frameworks

ISO 27001, ISO 27701, SOC 2

Data categories

pii, government-id

Scope

narrow

Risk rating

7

Platform compatibility

Purview: Compatible, GCP DLP: Compatible, Macie: Compatible, Zscaler: Compatible, Palo Alto: Compatible, Netskope: Compatible

Pattern

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

Corroborative evidence keywords

alien registration number, alien number, A-Number, A#, USCIS, USCIS number, green card, permanent resident, immigration, Form I-9, E-Verify, EAD, department of homeland security

Proximity: 300 characters

Should match

• Alien Registration Number: A012345678 — Labelled compact 9-digit A-Number
• A-123-456-789 — Grouped A-Number with hyphen separators
• USCIS Number A98765432 — Compact 8-digit A-Number with USCIS label

Should not match

• A1234567 — Only 7 digits after A in compact form (below the 8-digit minimum)
• AB12345678 — Two leading letters, not a single "A" prefix
• Please review the alien registration policy before the meeting — Prose mentioning alien registration with no number value

Known false positives

• Internal reference codes, asset tags, or invoice numbers of the form "A" + 8-9 digits in logistics or accounting systems unrelated to immigration. Mitigation: Require corroborative USCIS/immigration keywords (alien number, green card, Form I-9, USCIS) within the proximity window to confirm an immigration-records context.
• Catalogue or part numbers in technical documentation that share the A+digits shape. Mitigation: Combine with document-type detection (HR / immigration forms) and placeholder-marker exclusion.

References

• A-Number / Alien Registration Number (A-Number or A#) - USCIS