Political Parties Act Article 4

Political parties shall base their organizations in the free area of the Republic of China and are permitted to establish branch offices.Political parties shall establish their head office in the area stipulated in the preceding paragraph as the location where they shall base their organization.
中文原文 政黨法第4條
政黨以中華民國自由地區為其組織區域,得設立分支機構。
政黨之主事務所,應設於前項組織區域內。

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