The Enforcement Rules of the Motion Picture Act Article 9

When the copyright or distribution right of a motion picture is transferred, the transferee shall apply to the central competent authority for a change to be made to the ratings documents by submitting an application form, the original ratings document, the transfer contract, and the requisite fee.The permitted period of public screenings on the original ratings document shall remain the same on the re-issued ratings document.
中文原文 電影法施行細則第9條
電影片之著作財產權或發行權讓與時,受讓人應填具申請書並檢附分級證明文件及讓與契約書,連同規費,向中央主管機關申請換發分級證明文件。
前項換發之分級證明文件所載公開映演之有效期間,以原分級證明文件所載有效期間為準。

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