In the Name of Allah, the Most Gracious, the Most Merciful.
As-Salāmu ‘Alaykum Wa-Rahmatullāhi Wa-Barakātuh.
If a person wakes up thinking it is still Sehri time and starts eating, but later realizes that Fajr had already begun, then the fast for that day does not count. However, he should refrain from eating, drinking, etc. until sunset and Qada will be necessary, but there is no Kaffarah.[1]
And Allah Ta’ala Knows Best.
Abdour-Rahmaan Lim Voon Heek
Student Darul Iftaa
Port-louis, Mauritius
Checked and Approved by,
Mufti Muhammad Zakariyya Desai.