Labor Pension Act Article 15

Those hired by the same employer or those who voluntarily contribute to their labor pension in accordance with Article 7, Paragraph 2 or Paragraph 3 of the preceding Article may adjust their contribution rate within one year, however such adjustments shall be limited to two times. Upon adjustment, the employer shall fill out a contribution rate adjustment form and submit it to the Bureau of Labor Insurance before the end of the month that the adjustment is made, and the adjustment shall become effective on the first day of the month following the submission; the contribution rate shall be counted to the first decimal point of a percentage.For workers whose wages are adjusted between February to July of the current year, the employer shall notify the Bureau of Labor Insurance of the monthly contribution wage upon adjustment by the end of August of the current year; when the adjustment is made between August of the current year to January of the following year, notification to the Bureau of Labor Insurance shall be made by the end of February of the following year; All adjustments shall become effective from the first day of the following month after the notification.When an employer files a falsified monthly contribution wage for workers designated by Article 7, Paragraph 1 or fails to adjust the monthly contribution wage in accordance with the preceding paragraph, the Bureau of Labor Insurance may take the liberty to correct or adjust after verification and notify the employer concerned. The correction or adjustment shall become effective retroactively from the date contribution payments began or from the first day of the following month following the supposed adjustment.
中文原文 勞工退休金條例第15條
於同一雇主或依第七條第二項、前條第三項自願提繳者,一年內調整勞工退休金之提繳率,以二次為限。
調整時,雇主應於調整當月底前,填具提繳率調整表通知勞保局,並自通知之次月一日起生效;其提繳率計算至百分率小數點第一位為限。
勞工之工資如在當年二月至七月調整時,其雇主應於當年八月底前,將調整後之月提繳工資通知勞保局;如在當年八月至次年一月調整時,應於次年二月底前通知勞保局,其調整均自通知之次月一日起生效。
雇主為第七條第一項所定勞工申報月提繳工資不實或未依前項規定調整月提繳工資者,勞保局查證後得逕行更正或調整之,並通知雇主,且溯自提繳日或應調整之次月一日起生效。

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