henkilötunnus

Henkilötunnus, often abbreviated hetu, is the Finnish personal identity code. It is a unique identifier assigned to individuals who are registered in Finland’s population information system. The code is used by authorities and many private sector services to identify a person in encounters such as taxation, health care, social security, education, and official records. It helps link a person’s data across different registries and services.

Format and components: The code consists of 11 characters in the form DDMMYYCZZZX, where DDMMYY is the date of birth; C indicates the century: + for the 1800s, - for the 1900s, and A for the 2000s. ZZZ is a three-digit individual number; the digits in the individual number also signal gender (odd numbers typically indicate male, even indicate female). The final character is a check character derived from a modulus-31 calculation on the numeric part and ensures validity of the code.

Scope and privacy: The hetu is considered personal data. Its use is regulated by Finnish data protection laws and requires legitimate grounds. In practice, the code is widely requested and used across public services, healthcare, banks, and telecommunications to identify a person and access records. It is designed to be stable over a lifetime, and the same hetu remains with the person.

History and significance: The system has been established to support coordinated administration and service delivery in Finland. The hetu is the standard national identifier for residents and is central to many administrative processes and digital services.