All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
The one who is unable to fast in Ramadan due to an incurable disease must offer a compensation for each day of fasting that he misses. Allaah says (what means): {... And upon those who are able [to fast, but with hardship]—a ransom [as substitute] of feeding a poor person [each day].} [Quran 2: 184]
Ibn ‘Abbas and others maintain that this verse pertains to the elderly. The same applies to someone who suffers from a chronic disease that makes him permanently unable to fast. People with those illnesses may break their fast in Ramadan a poor person for each day of fasting that they miss.
The amount of the compensation that is to be paid is one mudd of food. The mudd is a unit of measurement that equals 750 grams according to Maliki and Shafi‘i scholars. The majority of the Muslim scholars maintain that the compensation must be given as food. Hanafi scholars, however, maintain that it is permissible to pay the compensation in money. We tend more to adopt the opinion of the majority of the Muslim scholars. Yet, there is nothing wrong with paying the compensation in money in cases in which money is more beneficial than food. The compensation for the entire month maybe paid all at once either at the beginning or at the end of the month. The compensation can also be paid on a daily basis.
Allaah Knows best.