Yes you have to pay fee at IIT the tuition fee at it is 1 lakh rupees per semester and other pays including hostel rent and mess advance sums up to 20000 per month.

SC ST students are given full waiver in tuition fee apart from that students are divided into three groups based on their family income,and if your family income are less than 1 lakh you are given full waiver in tuition fee from 1 to 4.5 lac are given 66% waiver in tuition fee.