Primary and Junior High School Act Article 16

School principals are appointed on a fixed-term basis. The term of appointment is four years for a public school principal, and the principal may be appointed for one consecutive term at the same school. Principals may return to a teaching position after their term of appointment expires. However, a principal who will reach retirement age within a year after their term of appointment expires may, with the approval of the selection committee and of the competent authority after the proposal is reported to it, continue to serve as principal until their retirement. The associated directions shall be prescribed by the respective competent authorities.The term of appointment for principals of schools in indigenous areas shall be prescribed by the special municipality or county (city) competent authority.With the exception of the term of appointment referred to in the proviso in Paragraph 1, the term of appointment for principals of special municipality and county (city) schools may be extended to fit in with the beginning and end of the school year, schools if the selection committee agrees and submits its decision to the special municipality or county (city) competent authority and approval is given. The associated directions shall be prescribed by the special municipality or county (city) competent authority.The directions governing the term of appointment and consecutive terms of appointment of private school principals shall be prescribed by the board of directors of the school legal person.
中文原文 國民教育法第16條
學校校長應採任期制,公立學校校長一任四年,得在同一學校連任一次,任期屆滿得回任教職。
但任期屆滿後一年內屆齡退休者,經遴選會通過,報經各該主管機關核准,得續任原學校校長職務至退休之日;其相關規定,由各該主管機關定之。
原住民族地區之學校校長任期,由直轄市、縣(市)主管機關定之。
第一項但書以外之直轄市、縣(市)立學校校長任期為配合學年起訖期間,得經遴選會通過,報直轄市、縣(市)主管機關核准,延長至任期屆滿之當學年終了之日止;其相關規定由直轄市、縣(市)主管機關定之。
私立學校校長之任期及連任之規定,由學校法人董事會定之。

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