US Passport Number

Detects US passport numbers, which consist of 8 to 9 digits optionally preceded by a single uppercase letter. Older US passports use a 9-digit numeric format, while newer passport books and cards may include a single alpha prefix followed by 8 digits. Due to the relatively simple format, corroborative keyword proximity is strongly recommended to reduce false positives.

Type

regex

Engine

boost_regex

Confidence

medium

Confidence justification

The US passport number format is short and loosely structured, consisting of an optional letter followed by 8-9 digits. This simplicity means the pattern can match many unrelated numeric strings such as reference codes, invoice numbers, and account identifiers. Medium confidence is appropriate; strong corroborative keyword proximity is essential for reliable detection.

Detection quality

Verified

Jurisdictions

us

Regulations

CCPA/CPRA, HIPAA, State Breach Laws (US)

Frameworks

ISO 27001, ISO 27701

Data categories

pii, government-id

Scope

narrow

Platform compatibility

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

Pattern

\b[A-Z]?\d{8,9}\b

Corroborative evidence keywords

passport, passport number, passport no, travel document, australian passport, ID number, identification, ID card, license, permit, registration, certificate

Proximity: 300 characters

Should match

• A12345678 — Letter-prefixed 8-digit US passport number (newer format)
• 123456789 — Nine-digit numeric US passport number (older format)

Should not match

• AB12345678 — Two-letter prefix is not a valid US passport number format
• 1234567 — Only 7 digits, which is below the minimum length for a US passport number

Known false positives

• Other 8-9 digit numbers such as order IDs, reference codes, phone numbers, and account identifiers Mitigation: Require strong corroborative keyword proximity (e.g., 'passport', 'travel document') within 300 characters to confirm the match as a genuine passport number
• Reference codes and serial numbers with an optional single-letter prefix Mitigation: Cross-reference with document context and additional entity detection to distinguish passport numbers from generic alphanumeric identifiers