The obligation to fast is upon who is fit to fast and satisfies the conditions for taklif (religious accountability). For individuals with dementia and medical conditions that significantly inhibit their ability to fast, he must pay fidyah for the missed fasts rather than attempt to make up the days through actual fasting.

Compounded payment is no longer a requirement for the previously missed fast. Sheikh al-Dimyāṭī al-Shāfiʿī in Iʿānah al-Ṭālibīn mentions that an affected person can be exempted for as long as the condition persists, even if it continues for years. This exemption recognises that dementia constitutes a valid ongoing excuse that prevents both the performance of fasts and the timely making up of missed days.