From the U.S. Embassy & Consulate in Korea website (https://kr.usembassy.gov/)
All male citizens of the Republic of Korea (ROK), including dual nationals, have military service responsibilities in accordance with the Korean Constitution and the Military Service Law.
Korea’s Military Manpower Administration is responsible for implementation and enforcement of regulations related to military service responsibilities. The following details related to military service have been provided by Korean officials:
- Males with multiple citizenships must choose their nationality by March 31 of the year they turn 18. Those who fail to do so are subject to military service obligations.
- Male ROK nationals who were born in the ROK but later acquire a foreign citizenship automatically lose their ROK citizenship and are no longer subject to Korean military service, whether or not they notify their loss of nationality to the relevant Korean authorities. However, if these individuals did not abide by military service procedures prior to naturalizing, such as obtaining the necessary overseas travel permits, they may be subject to fines, penalties, and/or incarceration upon return to the ROK.
- All male ROK nationals between the ages 25-37, including dual nationals, must obtain overseas travel permits from the MMA if they have not completed their military service and wish to travel overseas. These permits allow applicants to postpone their military service duty up until the age of 37. Those who lived overseas before age 25, must apply for these permits by January 15 of the year they turn 25. Applications may be made through a Korean embassy or consulate.
- There are different categories under which dual nationals qualify for an overseas travel permit, with classification determined by factors including parents’ citizenship or residency status, time spent abroad, and time spent in Korea.
- In cases where an applicant obtained a travel permit based on their parents’ overseas residency status and the parents have now returned to the ROK, the permit can be cancelled and the applicant subject to military service.
- An overseas travel permit can be cancelled and an applicant subject to military service if an applicant lives in the ROK for at least six months in a period of one year, or has engaged in for-profit activities in the ROK for a total of 60 days or more during a one year period.
For more complete information, please refer to the Military Manpower Administration website www.mma.go.kr (English available). The MMA Overseas Travel Procedure Guidebook and your local consulate may also provide useful information for male dual nationals.