Enforcement Rules of the Act Governing Relations with Hong Kong and Macau Article 5
When the Residents of Hong Kong apply for entry into the Taiwan Area, or claim their status as Hong Kong Residents in the Taiwan Area, relevant authorities may request such Hong Kong Residents to explain the fact of their not holding British (Overseas) passports or travel documents other than the Hong Kong passport, or to provide evidence thereof.
中文原文 香港澳門關係條例施行細則第5條
香港居民申請進入臺灣地區或在臺灣地區主張其為香港居民時，相關機關得令其陳明未持有英國國民（海外）護照或香港護照以外旅行證照之事實或出具證明。