The Official Website of Grand Ayatollah Makarem Shirazi

If one is obligated to observe kaffārah, but they are not able to observe it fully, they cannot abandon the amount they can observe. For instance, as for ‘Amd kaffārah, if one does not have the ability to fast for 60 days, nor can they afford to feed 60 needy persons, then they must abide by the following instructions. 1. They should feed as many poor people as they can. 2. If they cannot feed the poor, they must fast for 18 days. Yet, in this case, it is not necessary to fast for 18 consecutive days. 3. If one cannot fast for 18 days, then they can fast for as many days as they can. 4. Even if fasting is not possible for them either, they must do Istighfār. Yet, they do not have to put it in to words. In this case, even if they are able to observe kaffārah later, it will no longer be obligatory upon them to do so. If one is obligated to observe the Jam’ kaffārah, but they cannot fast for 60 days, nor can they feed 60 poor people, then they should fast for as many days as they can, and feed as many poor people as they can afford. If one does not have the ability to observe kaffārah, it is not necessary that someone else do it on their behalf, as everyone's kaffārah is obligatory only upon themselves. Therefore, if kaffārah becomes obligatory upon a woman, her husband does not have the obligation to pay her kaffārah, and the woman should perform kaffārah once she becomes able to. Similarly, if kaffārah is obligatory upon parents, their sons and daughters have no responsibility for observing kaffārah, and it is not even permissible to take kaffārah out of the very property bequeathed to heirs by their deceased parents, unless the matured heirs give their consent to paying kaffārah out of their own share of inheritance, or the parents themselves have made a will, in which case the kaffārah is taken out of their properties, provided that it does not exceed one third of the properties.