Act Governing Retirement, Severance, and Bereavement Compensation Under the Individual Account System for the Teaching and Other Staff of Public Educational Institutions Article 16

When a person who has previously received any retirement and benefit payments or other retirement or separation pay is subsequently reemployed as a staff member, that staff member is not permitted to return any payment already received. When the staff member once again retires or is dismissed with severance pay their years of service in employment shall be calculated from the date of their reemployment.
中文原文 公立學校教職員個人專戶制退休資遣撫卹條例第16條
已領退撫給與或退離給與人員再任教職員時,不得繳回已領之給與;其重行退休、資遣時,應自再任之日起計算其任職年資。

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