Question: When should a Masbooq stand up to complete his missed Rakaats?

Answer: It is recommended that the Masbooq stand up to complete  missed Rakaats, after the Imaam makes both Salaams.

 لان اوان قيامه للقضاء بعد خروج الامام من الصلاة فينبغي ان يؤخر القيام عن السلام [بدايع ج1ص424]

AND ALLAH KNOWS BEST

Yusuf Moosagie