May Allah accept our fasting in Ramadan! We are grateful that we have had the opportunity to pray taraweeh in the mosque this year. As always, we have enjoyed the fasting of Ramadan and are sad that it has come to an end. However, Allah in His infinite Generosity has given us an opportunity to fast a few more days and magnify the reward immensely.
It is recommended to fast for six days after Ramadan in the month of Shawwaal after the day of Eid so this is usually from the 2nd to the 7th of Shawwaal, but can be done anytime in the month of Shawwaal. The reward for fasting these six days is like fasting for a year, or in some reports, a lifetime.
Abu Ayyub al-Ansari narrated that Allah’s Messenger (ﷺ) said: He who observed the fast of Ramadan and then followed it with six (fasts) of Shawwaal, it would be as if he fasted perpetually. [Sahih Muslim Hadith 2614]
Some scholars have explained that fasting six days of Shawwaal after fasting Ramadan makes it as if one has fasted for an entire year of obligatory fasts, because the multiplication of the reward applies even to naafil fasts. Each hasanah brings the reward of ten like it, so fasting for thirty days of Ramadan multiplied by ten is 300. The six days of Shawwaal complete it to 360.
As a note, any fasts missed in Ramadan should be made up before fasting the days of Shawwaal, and the intentions cannot be mixed as they can for other voluntary fasts. This is because the narration mention that the fasts of Shawwaal follow the fasts of Ramadan, rather than running concurrently.
It is best therefore to complete outstanding fasts as soon as possible.
in summary, the preferred view is that it is better if they are done early and consecutively, but do not need to be. They can be completed anytime within the month of Shawwaal.
May Allah accept all of our deeds.