Islamic laws on fasting according to the Fatwas of the Grand Ayatollah Sistani.
Recompense (Kaffarah) of a fast
Ruling 1630: The Kaffarah for breaking a fast (Iftar) unlawfully in the Month of Ramadhan is that the person must free a slave, or fast for two months in accordance with the instructions that will be mentioned in the next ruling, or feed sixty poor people (Fuqara) or give each one of them a Mudd – which is approximately 750 grams – of food, i.e. wheat, barley, bread, or suchlike. In the event that none of these are possible for the person, he must give charity to the extent that he can. If this is not possible either, he must seek forgiveness from Allah (SWT); and the obligatory precaution is that he must give Kaffarah whenever he is able to.
source:shafaqna