Loss/retention of German citizenship
Source: BUS Rheinland-PfalzA German citizen loses their citizenship when they voluntarily acquire a foreign citizenship (Section 25 (1) sentence 1 of the Citizenship Act - StAG). In addition to an application for naturalization, voluntary acquisition also includes acquisition on the basis of an option, registration or declaration.
The loss of German citizenship does not occur if the German acquires the citizenship of another member state of the European Union, Switzerland or a state with which the Federal Republic of Germany has concluded a corresponding treaty under international law - there are currently no such treaties under international law (§ 25 Para. 1 Sentence 2 StAG).
In all other cases, the loss of German citizenship is only avoided if written permission to retain German citizenship has been granted prior to the acquisition of foreign citizenship. Subsequent approval is not possible.
The decision in the retention procedure must be awaited before the other nationality is accepted or acquired. Otherwise, German citizenship is automatically lost by law when the foreign citizenship is acquired, e.g. through naturalization.
The retention permit should be kept carefully, as it serves as proof of continued German citizenship despite the acquisition of another citizenship. Descendants who derive their German citizenship may also have to be able to prove this one day.