What is a French Social Security Number?

A French Social Security Number, known as the NIR (Numéro d'Inscription au Répertoire), is a unique 15-digit identifier assigned to every person born in France or affiliated with the French social security system. Often called "numéro de sécu" or referenced on the "Carte Vitale," this number encodes personal information including gender, birth year and month, place of birth, and a control key for validation.

The NIR structure follows a specific format: the first digit indicates gender (1 for male, 2 for female), followed by birth year (2 digits), birth month (2 digits), department or country code (2-3 digits), commune code (3 digits), registration number (3 digits), and a 2-digit control key calculated using modulo 97.

Tool description

This tool validates and parses French Social Security Numbers (NIR). Enter a 15-digit French SSN in any format—with or without spaces—and the tool instantly verifies its validity by checking the control key. For valid numbers, it extracts and displays all encoded information including gender, birth date details, birth location (country, department, and city INSEE code), and the formatted version of the number.

Features

  • Instant validation - Verifies the control key using the official modulo 97 algorithm
  • Complete parsing - Extracts all encoded data: gender, birth date, and location
  • Flexible input - Accepts SSN with or without spaces, dashes, or other separators
  • Location decoding - Identifies birth country, department (county), and city INSEE code
  • Auto-formatting - Displays the properly formatted SSN with standard spacing

Use cases

  • Healthcare administration - Verify patient SSN accuracy before processing medical claims or insurance documents
  • HR and payroll - Validate employee social security numbers during onboarding for compliance with French labor regulations
  • Identity verification - Cross-check declared birth information against SSN-encoded data for fraud prevention
  • Data entry validation - Ensure SSN correctness when digitizing paper records or migrating legacy databases