Question: If the month of Shawwaal starts and a woman has five missed days of fast and she wants to fast six days from Shawwaal. What is the better course of action: to make up for her missed days of fast, and if there are enough days left, she can fast six days from Shawwaal, or to fast the six days of Shawwaal and afterwards make up for her missed days of fast over the course of the other months? Is it true that `Aa’ishah (may Allaah be pleased with her) used to delay making up for her missed days of fast in Ramadaan until the next Sha`baan? Is it permissible to delay observing compensatory fast for this long period when a person does not know how long they will live?
Answer: It is permissible for a person to start observing compensatory fast even if they miss fasting six days from Shawwal… read more here.