The Imams of all schools are united on the time of Fajr which is the time to end the eating of Sehri. The time for Fajr begins when the sun is 18 degrees below the Horizon as has clearly been proven in Dar Al-Qubh An Waqt Al-Subh by the great Imam Ahmad Raza (Allah is pleased with him). Those people who continue eating after that time has passed, whether that be by mistake or due to following the wrong time table (whether it has been wrongly verified by a Mufti or an Aalim) have not fasted that day. They will have to do Qaza and no Kaffarah is upon them. This is clear in the book of fasting according to our Fuqaha.

And Allah knows best.

Zahid Hussain Al-Qadri