The World Federation One Stop Fiqh

Ruling 1631

Someone who wants to fast for two months for the kaffārah of the month of Ramadan must fast one complete month and one day from the next month continuously. Similarly, based on obligatory precaution, he must fast the rest of that second month continuously. If an obstacle arises that would commonly be considered a legitimate excuse, he does not have to fast that particular day, but once his legitimate excuse expires, he must resume his fasts.