Regulations Governing Educational Institutions at All levels Applying for Work Permits for Foreign Teachers and Their Administration Article 14

A foreign teacher who applied for employment and was approved in accordance with related ordinances before the enforcement of these Regulations may continue to be employed until the end of the period that they were engaged for.
中文原文 各級學校申請外國教師聘僱許可及管理辦法第14條
本辦法施行前,已依有關法令申請核准聘僱之外國教師,得繼續聘僱至聘期屆滿。

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