Enforcement Rules of the Nationality Act Article 19

The competent authorities as referred to in Paragraph 1 of Article 20 of this Act refer to those organizations that have the authority to employ the said civil servant.An R.O.C. national, having acquired a foreign nationality in accordance with Paragraph 1 of Article 20 of this Act, shall be prohibited from holding public office in the R.O.C.. This provision shall also apply to any foreigner who has acquired R.O.C. nationality without losing his/her original foreign nationality.Those who hold public office prescribed in the Proviso of Paragraph 1 and Paragraph 2 of Article 20 shall be subject to the recognition of the competent authorities.
中文原文 國籍法施行細則第19條
本法第二十條第一項所稱各該機關,指有權進用該公職人員之機關。
本法第二十條第一項所定中華民國國民取得外國國籍者,不得擔任中華民國公職之規定,於外國人取得我國國籍,仍保留外國國籍者,亦適用之。
本法第二十條第一項但書及第二項所列職務之人員,由各該管主管機關認定之。

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