Can a person start fasting six days of Shawwaal when he still has days to make up from Ramadaan?

If a person fasts six days of Shawwaal after Ramadaan when he has not yet completed the Ramadaan fast because he did not fast ten days of Ramadaan for a legitimate reason will he have the same reward as a person who fasted all of Ramadaan and followed it with six days of Shawwaal, i.e. will he be like a person who fasted for a lifetime? Please explain to us, may Allaah reward you with good.

Praise be to Allaah.

The precise rewards for the deeds which people do for the sake of Allaah is something which is known only to Allaah. If a person seeks the reward from Allaah and strives to obey Him, his reward will not be lost, as Allaah says (interpretation of the meaning):

“We shall not make the reward of anyone who does his (righteous) deeds in the most perfect manner to be lost.” [al-Kahf 18:30]. If someone has missed some of the days of Ramadaan, he should fast them first, then fast six days of Shawwaal, because he cannot follow the fast of Ramadaan with six days of Shawwaal unless he has completed his Ramadaan fast.

And Allaah is the source of strength. May Allaah bless our Prophet Muhammad and his family and companions, and grant them peace.

Fataawa al-Lajnah al-Daa’imah, 10/392