In order to establish the existence of German citizenship, it is necessary, but also sufficient, if it can be proven with sufficient probability by documents, extracts from the population registers or other written evidence that you have acquired German citizenship and have not lost it again.
The following documents may be useful:
- Documents relating to parentage and marital status: birth certificates, marriage certificates;
- Documents on the acquisition of German citizenship: naturalization certificates, conferral certificates, admission certificates, certificates/documents on the acquisition of German citizenship by declaration or option, appointment certificates for civil servants, assessment certificates on the acquisition of citizenship through service in the former German armed forces and other associations;
- Documents concerning membership of the group of persons to whom a collective naturalization extended: expellee identity cards, late repatriate certificates, ethnic list identity cards, certificates of ethnicity or other documents concerning German ethnicity, proof of (former) right of origin, citizenship or residence in the areas concerned, certificates of waiver of the right of renunciation;
- Documents concerning the acquisition of legal status as a German without German citizenship: expellee identity cards, late repatriate certificates, (old) refugee identity cards, registration certificates, registration confirmations or registration certificates;
- Documents concerning possession of German citizenship or legal status as a German: proof of citizenship, certificates of origin, documents/ID cards concerning legal status as a German, passports, identity cards and other identification documents (including old ones), extracts from (former) family registers, lists of citizens or citizen directories, documents concerning military service or employment as a civil servant, registration confirmations, registration certificates, documents concerning authorization to retain German citizenship.
Bring what you have with you, the citizenship authority will help you to look through it.