Art. 22 SCA from 2019

Art. 22 Persons who erroneously believe they are Swiss citizens
1 Any person who has believed in good faith for five years that he or she is a Swiss citizen, and has in practice been treated during this period by the cantonal or communal authorities as a Swiss citizen, may apply for simplified naturalisation.
2 The naturalised person acquires the cantonal citizenship of the canton responsible for the error. This canton shall decide which communal citizenship the person acquires at the same time.
Es besteht kein Anspruch auf Aktualität und Vollständigkeit/Richtigkeit.