CPR-nummer

Detects CPR-nummer patterns. This pattern is based on a Microsoft Purview built-in sensitive information type. Users already running Purview may prefer to enable the built-in SIT directly, or use this version as a starting point for customisation.

Type

regex

Engine

universal

Confidence

medium

Confidence justification

Medium confidence: pattern has structural constraints but corroborative keywords are recommended to reduce false positive rates. Context label evidence plus explicit template/example exclusion improves precision for high-risk identifiers. Added context gating and exclusion rules improve precision and reduce incidental matches.

Detection quality

Verified

Jurisdictions

eu, dk

Regulations

BDSG, CNIL / LIL, GDPR

Frameworks

ISO 27001, ISO 27701

Data categories

pii, government-id

Scope

narrow

Risk rating

9

Platform compatibility

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

Pattern

\b\d{6}-?\d{4}\b

Corroborative evidence keywords

CPR, personnummer, personal identification, ID number, identification, ID card, license, permit, registration, certificate, data record, database record, record set, data extract, data export, database table, spreadsheet, data registry, registry entry, master data (+13 more)

Proximity: 300 characters

Should match

• 010175-1234 — CPR number with dash
• 1201881234 — CPR number without dash
• 150392-5678 — Another CPR number with dash

Should not match

• 01017-1234 — Too few digits in first part
• 010175-12345 — Too many digits in second part
• sample template placeholder number 123456789 — Template/sample context should be excluded even when numeric-like values appear
• template example placeholder record identifier — Template/sample context should be excluded even when anchor words are present

Known false positives

• Ten-digit sequences with optional dash may match dates, phone numbers, or administrative reference codes. Mitigation: Require corroborative evidence keywords such as "CPR" or "personnummer" within the proximity window.
• In Australian tenants, Australian mobile telephone numbers can satisfy this ten-digit structure and create cross-SIT numeric identifier overmatch. Mitigation: Use the AU mobile number NONE-of regex gate where phone numbers are not valid positive evidence.
• In multiple languages, similar terminology used in formal or administrative contexts (education, professional documentation) that does not constitute sensitive data collection. Mitigation: Layer with additional contextual signals such as structured identifiers, form fields, or database column headers to distinguish sensitive records from general references.

References

• Denmark Personal Identification Number entity definition - Microsoft Learn