B1 for German Citizenship: Which Language Proof You NeedFor German citizenship you must normally prove German at level B1 under §10 of the Nationality Act. A Goethe, telc or ÖSD B1 certificate counts, as does a DTZ result at B1 or a German school, vocational or university qualification. Exceptions exist for age, illness and the guest-worker generation. B1, not C1, is the standard.