The Korean citizenship law primarily recognizes ius sanguinis, meaning that whoever is born to a Korean national immediately becomes a Korean citizen regardless of where he or she was born. On the other hand, the Korean citizenship can only be granted on the basis of ius soli principle when the parents of a child born in Korea are unknown or have no nationality, and in case an abandoned child was found in Korea.
Other than by birth, Korean citizenship may also be obtained by acknowledgement (by a Korean parent), naturalisation (general, facilitated, special) and recovery of nationality.
As a rule, dual citizenship in Korea is not allowed. The law explicitly states that one who has acquired Korean citizenship must renounce the citizenship of another country within one year, while Korean nationals lose their Korean citizenship as soon as they acquire a foreign one.
There are, however, exceptions to this rule. Dual citizenship may be permitted if: a person acquires Korean citizenship as a spouse of a Korean national; a person has contributed greatly to the Republic of Korea; a person has outstanding abilities in a specific field, such as science, economy, culture, and sport; or a person finds it difficult to renounce his or her citizenship because of the laws and procedures of his or her country. There are also exceptions regarding certain former Korean nationals who want to reinstate their Korean citizenship.
Dual citizenship is allowed only for the categories of people stated above and only if they vow their intention not to exercise the foreign citizenship in Korea.
The obligation to renounce a citizenship should also be the right for those dual citizens who want to do so. However, the Korean law does not always permit renunciation when it comes to the Korean citizenship. Because of the mandatory conscription system, in Korea male citizens must choose the desired citizenship before the end of March of the year when they turn 18. Otherwise, Korean citizenship, if kept, can only be renounced either upon the fulfilment of the military duty or at the age of 38.