Administrative Appeal Act Article 46

A service shall be made to the administrative appeal representative unless the authorization to receive an service is limited. However, service might have made to the administrative appellant or intervenor appellant, while the agency with jurisdiction of administrative appeal deemed necessary.
中文原文 訴願法第46條
訴願代理人除受送達之權限受有限制者外,送達應向該代理人為之。
但受理訴願機關認為必要時,得送達於訴願人或參加人本人。

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