Customs Personnel Management Act Article 6

The rank promotion of customs officers may be conducted, mutatis mutandis, in accordance with promotion by performance rating related regulations of Civil Service Performance Evaluation Act.
中文原文 關務人員人事條例第6條
關務人員官階之晉升,準用公務人員考績法考績升職等之規定。

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