Constitutional Court Procedure Act Article 4

The Judicial Yuan shall make the Rules of the Constitutional Court.The Rules referred to in the preceding Paragraph shall be adopted by all Justices.Where the number of incumbent Justices falls short of the number prescribed in Article 5, Paragraph 1 of the Additional Articles of the Constitution due to expiration of term, resignation, removal from office, or death, the President shall submit nominees for all vacancies within two months.
中文原文 憲法訴訟法第4條
憲法法庭審理規則,由司法院定之。
前項規則,由全體大法官議決之。
大法官因任期屆滿、辭職、免職或死亡,以致人數未達中華民國憲法增修條文第五條第一項所定人數時,總統應於二個月內補足提名。

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