Those who are unable to fast due to a temporary excuse are required to make up (qaḍāʾ) the missed fasts once the excuse no longer exists. However, for those whose excuse is not expected to end—such as the elderly or individuals who are permanently unable to fast due to illness—Islam has prescribed a compensatory measure known as fidyah.
Fidyah consists of assistance given to the poor on behalf of the person with a valid excuse. For each missed fast, this entails providing a poor person with the equivalent of two meals—morning and evening—or giving the monetary equivalent of that food. This amount represents the minimum obligation; one may give more if they wish.
As with kaffārah, fidyah fulfills two purposes: it discharges the religious obligation of the person who is unable to fast and simultaneously serves as an act of social solidarity by supporting those in need.
If a person who has given fidyah due to an inability to fast later becomes capable of fasting again, they are required to make up (qaḍāʾ) the days for which fidyah had been given.