Regulations Governing Coordination & Liaison between Coast Guard Administration, Executive Yuan and Police, Immigration, & Fire Organizations Article 5

Any illegally entered citizen from the other states, mainland China, Hong Kong or Macao, or any national without household registration in the Taiwan Area arrested by the Coast Guard shall be forced to depart or transfer under guard to the custody place designated by the National Immigration Agency as required; however, the disposition of transfer under guard will be prevented in the event that the subject should be transferred to the judicial department for investigation and prosecution or in any extraordinary case as provided by the law.The alien rescued from disasters by the Coast Guard shall be transferred to the place designated by local competent units of the National Immigration Agency.After giving a prior notice to the regulating authorities and its management unit, the Coast Guard may assign its personnel to the designated place for subsequent interrogation with the subject.
中文原文 海岸巡防機關與警察移民及消防機關協調聯繫辦法第5條
海巡機關緝獲非法入國(境)之外國人、大陸地區人民、香港或澳門居民、臺灣地區無戶籍國民,應依規定強制出境或解送移民機關指定之收容所收容。
但依法應移送司法機關偵辦或具特殊情形者,不予解送收容。
海巡機關執行救難所救援之外國人,應移由移民機關當地權責單位處理。
海巡機關得派員至指定之處所複訊,但應事先知會業管及管理單位。

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