Steuer-ID, Bürger-ID, Sozialversicherungsnummer — was ist was?

Three numbers everyone confuses: Tax ID (IdNr): 11 digits, lifelong, sent automatically after registration. For taxes, employer, Kindergeld. Citizen ID / ID card number: on your ID card, for authorities. Social security number (pension insurance number): 12 characters, for social insurance. Arrives automatically with first job, otherwise request from Rentenversicherung. Where to find: Tax ID in BZSt letter, SV number on social insurance card or payslip.