The Enforcement Rules of the Land Tax Act Article 49

To calculate the total amount of land value increment pursuant to Article 32 of the Act, such evaluation shall be done according to Article 30 of the Act. The most recently announced overall consumer price index for the Taiwan Region. Upon receipt of the present value declaration at the year of transfer shall be used for adjustment of the originally prescribed land value or of the declared land current value at the previous transfer.
中文原文 土地稅法施行細則第49條
依本法第三十二條計算土地漲價總數額時,應按本法第三十條審核申報移轉現值所屬年月已公告之最近臺灣地區消費者物價總指數,調整原規定地價或前次移轉時申報之土地移轉現值。

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