Allah the most merciful has exempted some people from fasting in Ramadan. Some cases like; sick, old people, or travelers. And they have to make up for those days later and give compensation to the poor and needy.  

Exemptions from fasting

1- Illness and old age: A person who is ill and hopes to recover good health may not fast during the days when he is ill. When he is back in health he must fast the same number of days he did not fast in Ramadan, during the following eleven months.

The type of illness that gives the exemption from fasting is one which makes fasting hard.

A person suffering a chronic illness with little or no hope of recovery, and one who is permanently unable to fast such as a frail, elderly person, need not fast and are not required to fast later. What they are required to do is to give compensation in the form of feeding a poor person for every day when they did not fast. In the early days of Islam, when fasting was made a duty, Muslims were given the choice of either to fast or to feed one poor person for the day. Thus, Allah made the feeding of a poor person equal to fasting. This remains the case when exemption is permanent.

 Imam al-Bukhari mentions in his anthology of authentic hadiths: ‘Al-Hasan and Ibrahim mentioned that an elderly person who finds fasting too hard may feed a poor person. Anas did that for a year or two when he was too old: he fed a poor person in compensation for every day he could not fast.[1]

Regarding an elderly man or woman who finds fasting too hard,

Thus, a person who is permanently unable to fast, either because of a chronic illness or being elderly, should compensate for non-fasting by feeding a poor person. Scholars used to estimate that by a measure equal to 1.125 kilogram of wheat, rice, dates or the staple diet of one’s town. However, it is better to say that feeding a poor person should be of what one usually feeds his family,

 If an ill person fasts, his fasting is valid. 

2-Travel: A person on a journey is given the concession that he does not need to fast in Ramadan, but he must compensate for it by fasting the same number of days he did not fast during his travel.

Exemption from fasting is applicable to travel that covers a distance similar to that which allows shortening prayers.[2] This is estimated at about 80 kilometres. Another way of gauging it is according to what Muslims there consider as travelling.Moreover, travel must be for a legitimate purpose. If it is undertaken in order to commit a sinful action, or to dodge fasting, the exemption does not apply.

If a traveller choose to fast, his fasting is valid.

 It is a condition for fasting during travel that fasting should not cause hardship. If the person concerned finds fasting too hard or harmful, then it becomes prohibited and sinful to fast during travel. During his travel, the Prophet (peace be upon him) saw a man who was being given covering shade because it was too hot, and people gathered around him. When he was informed that the person was fasting,

3-Menstruation: When a woman is in her menstrual period, or having postnatal bleeding, she must not fast. In fact, if she fasts, her fast is invalid. Abu Sa'id al-Khudri mentions that the Prophet (peace be upon him) clearly stated that a woman in menstruation may neither pray nor fast. She is required to compensate by fasting later on. 'A’ishah said: ‘It happened to us and we were ordered to fast later in compensation, but not to compensate for missed prayers.’

4-Pregnancy and breastfeeding. A woman who is pregnant or breastfeeding and fears for herself or her child as a result of fasting, may not fast.

 Both pregnant and breastfeeding women must compensate for not fasting by fasting a similar number of days later on, or they can feed a poor person for each day they do not fast.