All perfect praise be to Allah, The Lord of The Worlds, and may His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
The majority of the Muslim scholars from the Maliki, Shafie and Hanbali legal schools are of the view that if a person delays making up for the days of fasting that he had missed in the previous Ramadan until the next Ramadan came, without a valid excuse, such a person is sinful and obliged to pay an expiation (Fidyah): One Mud (600-1000fils)* of food for each missed day. He is also obliged to make up for them. The evidence for this is the same opinion of six the Prophet's (PBUH) companions on the same issue and it wasn`t reported that none contradicted them.
Ibn Hajar Al-Haithami (May Allah have mercy on him) said: "The person who delays making up for the days of fasting that he had missed in the previous Ramadan, although he could have made up for them as he was neither sick nor traveling, until the next Ramadan came is obliged, along with making up for the missed days, to pay the value of one Mudd against each missed day. This is because six of the Companions have stated as such, and it wasn`t reported that any has ever contradicted them." [Tohfat Al-Mohtajj].
However, if the delay was due to a valid excuse, such as sickness, travel or ignorance of the prohibition of delaying making up for missed fasts until the next Ramadan, then he isn`t obliged to pay an expiation (Fidyah). Rather, he is only obliged to make up for the missed days. It was stated in the Shafie book [Boshra Al-Kareem]: "Delaying making up for obligatory fast missed for a valid excuse, such as travel, breastfeeding, forgetfulness and ignorance of the prohibition of delaying it, even by a Muslim living in a Muslim country…….Paying the expiation (Fidyah) isn`t an obligation."*
By this we arrive at the conclusion that the view of the majority of the Muslim scholars is based on the statement of the above Companions, and it is evident that their view wasn`t the result of Ijtihad. Rather, it was determined the Lawgiver. Therefore, acting upon this view takes more precedence and is more obligatory than the view of the Hanafis who said that the above man is only obliged to make up for the missed fasts.
Moreover, Al-Khasani (May Allah have mercy on him) said: "If a person delays making up for the days of fasting that he had missed in the previous Ramadan until the next Ramadan came, then no expiation (Fidyah) is due on him."[Bada`e` Al-Sanaea']. And Allah Knows Best. * {Added 2/2/2016}.