I intended to observe the six fasts of Shawwaal, along with the intention to make up for some missed fasts. After fasting four days, I was informed that this double intention was not valid. So, should I repeat the makeup fasts?

All perfect praise be to Allaah, the Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.

The correct opinion which we adopt in Islamweb is that it is invalid to combine the intention to observe the six fasts of Shawwaal with the intention of making up for missed fasts.

Therefore, the four days you have fasted with the combined intention of observing (four of) the six fasts of Shawwaal along with the intention to make up for the missed fasts will only count as fasts to make up for the missed fasts. Hence; it is not incumbent upon you to repeat the fast for those four days.

However, it would be better for you to repeat them to be on the safe side and to free yourself from liability, following the opinion that those days count as voluntary fasts, and not as make up fasts.

Allaah Knows best.