Fasting Ramadan is one of the pillars of Islam. Neglecting to observe it, thus, is a grave sin and a deep break in faith. How can a Muslim neglects one of the cornerstones of his religion? This is really a transgression of the sacred limits of Allah.
It is noteworthy in this regard to mention that a group of scholars hold the opinion that if a person neglects deliberately to observe fasting on a single day in Ramadan and has no legitimate excuse to do so, it will never be accepted from him/her to make up for it by fasting on any other day. They argued that every act of worship that is linked to a specific time is that if it is deliberately delayed beyond that time for no excuse, it will not be accepted, because the Prophet (peace and blessings of Allah be upon him) said: “Whoever does an action that is not in accordance with this matter of ours will have it rejected.”
however, the majority of scholars view that deliberately neglected fasting has to be made up for hoping that Allah will accept it and forgive such transgression of His boundaries. No other compensation is accepted instead as long as the person is able to fast.
as for breaking the missed days over periods of time, there is nothing wrong in do so keeping in mind that death if nearer to man than he/she thinks and that it is better not to meet Allah with such a debt.
We cannot conclude without reminding that the mercy of Allah has encompassed everything. The door of repentance is always wide open day and night. Indeed Allah loves those who return to him and it is He who accepts repentance from His servants and forgoes sins.