Does one who fasts six days of Shawwal in Dhu al-Qi'dah attain its special reward?

If a fasting person has a valid excuse such as illness, menstruation, postpartum bleeding, or the like, and delays making up missed fasts or observing the six days of Shawwal, they will still attain the special reward. However, if they have no excuse and delay fasting them until Dhu al-Qa'dah or later, they will not attain the special virtue, and the fast becomes a sunnah whose specific time has passed.