Every male Finnish citizen is liable for military service starting from the beginning of the year in which he turns 18 years old until the end of the year in which he turns 60. Women may also apply for service.
A call-up letter for military service will be sent to a male Finnish citizen living abroad. In the call-up letter there will be a place and time announced where the call-up will be organized. The call-up letter can be sent only if the person in question has updated his address to the Finnish Population Information System.
A person with dual/multi citizenship is liable for military service. He may apply for exemption from Finnish military service in peacetime by submitting a free-form letter addressed to the Regional Office of Helsinki or the Regional Office of the home municipality. Citizenship information has to be updated to the Finnish Population Information System.
Further information can be found on the website of Finnish Defence Forces.