Folkeregisteret

Also known as: National Population Register, fødselsnummer, national identity number

Norway’s official population register, run by Skatteetaten — issues the national identity number or D-number.

Folkeregisteret is Norway’s official population register, run by the Norwegian Tax Administration. It records:

The fødselsnummer (11-digit national identity number) for people resident more than 6 months.
The D-number (temporary 11-digit number) for people in Norway short term.
Address, marital status, parental responsibility.

The Norwegian welfare system — GP (fastlege), banks, NAV, health services — all rely on lookups in the register.