The Enforcement Act of Act of Military Service System Article 3

The male older than Conscription Age who have not gone through the conscription procedure shall go through the procedure and, after passing, be conscripted according to the order of their ages.
中文原文 兵役法施行法第3條
已逾徵兵及齡之男子,尚未經徵兵處理者,於補行徵兵處理合格後,依年次順序徵集入營。

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