Is a missed prayer that is being made up accepted, and what is its nature?

Missed prayers are either obligatory (fard) or supererogatory (sunnah). Obligatory prayers, such as the five daily prayers and Jumu'ah (Friday prayer, which is made up as Dhuhr), must be made up (qada'). Supererogatory prayers, such as the regular sunnah prayers (rawatib), are recommended to be made up according to some scholars. However, voluntary prayers (nawafil) that are tied to a specific reason whose time has passed, like the eclipse prayer (salat al-kusuf), the prayer for rain (salat al-istisqa'), or the greeting of the mosque (tahiyyat al-masjid), are not made up. A missed prayer must be made up immediately, whether it was missed intentionally, by oversight, or due to sleep. The acceptance of a made-up prayer is a matter of the unseen, known only to Allah.