The issue of Al-Qadaa (payback), Al-Fidya (ransom/substitution) and Al-Kafaara (expiation) all come about through the breaking of a fast of Ramadan or choosing not to fast at all. Different scenarios of breaking a fast/not fasting lead to different results, for it might be that the breaking of a fast leads only to ‘Al-Qadaa (payback), or only Al-Fidya (ransom). It could be that not fasting lead to a combination of the two, or a combination of Al-Kafaara (expiation) and Al-Qadaa (payback) – and we will try to mention all of these scenarios.
There is only one case scenario whereby a Muslim is not obliged to make up days that they have missed in Ramadan, and that is for the terminally ill or the extremely old aged who will never have the ability to fast again. If this is the case, they must feed a poor person every day that they missed, and this known as the Fidya (ransom), the next topic of discussion.
 The person still needs to make up the day of Ramadan that they broke, as the Kafaara does not cover the Qadaa.
And Allah (Subhana wa ta’ala) knows best