Act of Military Service System Article 3

A man aged 18 starts his military service day from January 1st of the proceeding year and be discharged on December 31st of the year at the age of 36, called the Male's Service Age. However, the discharged age of fficers , NCOs and volunteer soldiers are not restricted to this rule.The so-called Man of Approaching Service Age refers to the period from January 1st of the proceeding year of a man of 15 years old, to December 31st of the year he reaches the age of 18.
中文原文 兵役法第3條
男子年滿十八歲之翌年一月一日起役,至屆滿三十六歲之年十二月三十一日除役,稱為役齡男子。
但軍官、士官、志願士兵除役年齡,不在此限。
男子年滿十五歲之翌年一月一日起,至屆滿十八歲之年十二月三十一日止,稱為接近役齡男子。

English translation for reference only; the Chinese text prevails. Not legal advice.