Two Intentions (Niyyah) in Shawwal Fasting

Six days fasting in Shawwal is a recommended fasting and every Muslim should observe the fasting to get a reward from Allah. But for someone who missed several days in Ramadan fasting then they must make up for it, usually they do this in Shawwal month.

People often asking if someone has a fast of Ramadan to makeup, can he make it up on six days of Shawwal with two intentions (niyyah); to get the reward of fasting six days of Shawwal and making up his missed fasts of Ramadan?

The answer is yes. There is nothing wrong, as far as Islam is concerned in making a double intention (niyyah) by fasting the missed days of obligatory fasting in Ramadan as well as fasting the optional six days of Shawwal. However, some Muslim jurists state that it is recommended to make up for the missed fasts separately from fasting the six days of Shawwal so as to get extra reward.

The Shafi'i scholars maintained the Ijtihad and said someone will get two rewards when they are intended to fast for missed Ramadan fasting and six days of Shawwal fasting.

Sheikh `Atiyyah Saqr, former head of Al-Azhar Fatwa Committee, states the following:

A person who has missed days of fasting in Ramadan may fast the optional six days of Shawwal with the intention of both making up for these missed days and observing the optional fasting of six days of Shawwal. He or she will then get double benefit simultaneously: making up for the missed days and getting the reward of fasting the six days of Shawwal, for it is established in Islam that one's acts are judged by one's intentions.
However, it is recommended that one makes up for the missed fasts separately from fasting the six days of Shawwal [so as to get extra reward].
The Shafi`i scholars maintain that when one makes up for the missed fasts of Ramadan in Shawwal, one also gets the reward of fasting the optional six days of Shawwal even if one has not intended to fast those six days principally; yet the reward of fasting the six days here will be less than if one has intended to fast them from the beginning.
Based on the above, it is permissible for one to fast six days of Shawwal intending simultaneously both to make up for the fasts one has missed in Ramadan and to offer the recommended fasting of six days in Shawwal, especially if one is interested in getting the reward of fasting the six days of Shawwal with making up for the missed fasts of Ramadan but finds it exhausting to do both separately.
Besides, if one in this case intends only to make up for the missed Ramadan fasts in Shawwal (and it happens that these days are six or more), one will get also the reward of fasting the six days of Shawwal. The supererogatory act of fasting the six days of Shawwal here is sub-categorized under the obligation of making up for the missed fasts of Ramadan. This is an alleviation reasoned by jurists, and hence, there is no need for adopting a view of a certain school in this regard and judging the other views as wrong.

The Ijtihad would be the same if you are intended to have Monday-Thursday fasting and combined with six days Shawwal fasting, you will get both fasting reward, InshaAllah.

Conclusion: It is allowed to making double intention (niyyah) but it is recommended to make up for the missed fasts separately from fasting the six days of Shawwal so as to get extra reward.

References: Islamonline.net and other Islamic sites