Compulsory Education Act Article 8-1

Primary and junior high schools shall notify the competent education administration authority if they discover students being absent from school for 3 days or more without leave or without clear reason, or discover that transferred students have not yet reported to their new school to enroll. The students shall be counseled and resume attending school.The regulations governing submitting a report and return-to-school counseling shall be prescribed by the Ministry of Education.
中文原文 強迫入學條例第8-1條
國民小學及國民中學發現學生有未經請假或不明原因未到校上課達三天以上,或轉學生未向轉入學校報到者,應通報主管教育行政機關,並輔導其復學;其通報及復學輔導辦法,由教育部定之。

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