Administrative Litigation Act Article 69

Where the parties or agents have no domicile, residence, principal office or place of business in the R.O.C., they should appoint an agent of service and provide notice of such appointment to the administrative court in which the litigation is pending,
中文原文 行政訴訟法第69條
當事人或代理人於中華民國無住居所、事務所及營業所者,應指定送達代收人向受訴行政法院陳明。

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