Commercial Case Adjudication Act Article 37

An amendment, additional claims or a counterclaim to an action, pursuant to the provisions of Article 255 and Article 259 of the Taiwan Code of Civil Procedure, shall be made before the end of the preparatory proceedings. Where there are no preparatory proceedings, such an action shall be made before the date of the first oral argument session.
中文原文 商業事件審理法第37條
依民事訴訟法第二百五十五條、第二百五十九條規定為訴之變更或追加及提起反訴,應於準備程序終結前為之;未行準備程序者,應於第一次言詞辯論期日前為之。

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