Assalamualikum Sheikh, what does someone do if they have previously missed fasts and they won't be able to make them up due to not enough days left until next ramadan, So when new ramadan comes, should his intention be to fast this current year's ramadan or previously missed? Jazakallahukhair

Ustadh AbdulAziz al-Haqqan

Yes and he makes them up and expiates if he does not have a valid reason as is the fatwa of Imam Ibn Baz.