A person who became a mourner after the time for Shacharit or Mincha began and didn’t yet pray, some say he’s obligated to make Tashlumin and some argue [1]
Sources
↑ Mishna Brurah 71, Magen Giborim and Derech HaChaim hold that a person is chayav, while the Yad Efrayim (Aninut 29), Birkei Yosef 341:17, Chachmat Shlomo 71, and Sh”t Shevet HaLevi 6:11 hold that one is exempt from Tashlumin.