Regulations Governing the Establishment and Assistance of Overseas Taiwan Schools Article 28

The age of admission for students at an Overseas Chinese School shall be based on the regulations for admission to schools at a corresponding level in Taiwan. However, if the local elementary school academic year runs from January to December, the age of admission for school is children who will reach the age of six by December 31 of the admission year.The proviso in the preceding paragraph shall take effect on August 1, 2009.
中文原文 海外臺灣學校設立及輔導辦法第28條
海外臺灣學校學生入學年齡,依國內各級學校之規定。
但當地國國小學年起迄時間為一月至十二月者,其學齡兒童入學年齡,以計算至入學當年度十二月三十一日滿六歲者為準。
前項但書規定,自中華民國九十八年八月一日施行。

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