What is incumbent upon one who suffered from obsessive-compulsive disorder (OCD) regarding fasting for years and was unable to make up missed fasts due to hardship and suffering, and decided to make them up after recovering from OCD, which he is currently being treated for? And is he only required to make up the fasts, or both make up the fasts and offer expiation?

Whoever postpones making up the fasts due to an excuse until the next Ramadan (definition) begins is only required to make up the fasts and is not obligated to pay the fidyah (definition) (expiatory feeding). Obsessive-compulsive disorder (OCD), which makes making up the fasts difficult, is considered a valid excuse that permits delaying the make-up fasts. Therefore, there is no sin and no fidyah.