What is the expiation for breaking the fast for the entire month of Ramadan due to a medical excuse for a patient who is unable to fast throughout the year?

There is no expiation (kaffarah) for the sick person if they break their fast in Ramadan, even if they are unable to make up the days throughout the year, due to the Almighty's saying: ﴿But whoever among you is ill or on a journey [should fast] a number of other days﴾ [Al-Baqarah: 184].

If their illness is expected to be cured, they should wait until Allah cures them, and then make up the days they missed. However, if their illness is chronic and not expected to be cured—according to trustworthy doctors—then they must pay the fidyah (ransom) according to the majority of scholars, and it is recommended according to the Malikis. This fidyah is feeding one poor person for each day.