The current nationality regime in Finland is based on the Finnish Nationality Act of 2003 and its subsequent amendments. Acquisition of Finnish citizenship (kansalaisuus) is mainly based on the principle of ius sanguinis. Finnish citizenship can also be acquired by birth, by marriage, on adoption, provided that the adopted child is under the age of 12 and one parent is a Finnish citizen through legitimation, and through naturalisation by application or declaration. Finnish citizenship may never be lost if it leads to statelessness.
As of 2003, Finland accepts multiple citizenship, thus a Finnish citizen is able to acquire another nationality without losing the original nationality. As a consequence, those foreigners wishing to apply for naturalisation in Finland are no longer required to renounce their original citizenship upon acquiring Finnish nationality. Finnish law does not specify any consequences in relation to registration or renunciation conditions and Finnish citizens are therefore allowed to hold dual citizenship without any special conditions.