Postal Remittances and Savings Act Article 22
The right to cash a postal money order, if not exercised, shall be extinguished three years from the date it is issued.
中文原文 郵政儲金匯兌法第22條
郵政匯票受款人之兌領請求權，自發票日起算，三年間不行使，因時效而消滅。
English translation for reference only; the Chinese text prevails. Not legal advice.