Praise be to Allah.
If a person delays making up missed Ramadan fasts until the next Ramadan begins, then if that was for a reason such as sickness, pregnancy or breastfeeding and the like, then he or she does not have to do anything except make up the missed days. But if there was no excuse , then he or she has sinned and must make up for the missed days, but does he or she have to pay a fidyah or not? There is a difference of opinion among the scholars. The majority are of the view that the fidyah must be paid, and it is feeding one poor person for every day. In the answer to question no. 26865 , we stated that the more correct view is that the fidyah is not obligatory, but the one who pays it in order to be on the safe side has done well.
This fidyah – according to those who say that it is required – becomes obligatory upon that person as soon as the next Ramadan begins, and he may offer it at that time, or delay it until he makes up those fasts, but it is better to hasten to do it so as to fulfil his obligation.
It says in al-Mawsu’ah al-Fiqhiyyah (28/76):
“Making up missed Ramadan fasts may be done at any time but the majority of scholars limited it to a specific time frame within which they must be made up, which is before the next Ramadan begins, because of the words of ‘Aishah (may Allah be pleased with her): “I would owe missed Ramadan fasts but I would not be able to make them up except in Sha’ban, because of my duties towards the Prophet (peace and blessings of Allah be upon him).” This is similar to prayer, which should not be delayed until the time for the next prayer comes.
According to the majority of scholars, it is not permissible to delay making up missed Ramadan fasts until the next Ramadan comes without an excuse, and that doing so incurs sin, because of this hadith of ‘Aishah. If a person delays that then he must offer the fidyah: feeding one poor person for each day, because of the report narrated from Ibn ‘Abbas, Ibn ‘Umar and Abu Hurayrah (may Allah be pleased with them) who said concerning the one who has to make up a missed fast but does not do so until the next Ramadan comes: “He must make it up and feed one poor person for each day.” This fidyah is for delaying it. It is permissible to offer the food before making up the fast, at the same time, or afterwards.”
Al-Mardawi al-Hanbali (may Allah have mercy on him) said:
“He should offer food that is acceptable for expiation. It is permissible to give the food before making up the fast, at the same time, or afterwards. al-Majd – meaning Ibn Taymiyah, the grandfather of Shaykh al-Islam Ibn Taymiyah – said that the best is to give it beforehand, in his view, so as to hasten to do good and to rid oneself of the problem of postponing.” (Al-Insaf, 3/333)
And Allah knows best.