Depends your ticket is cnfd or not...
If wait list...min charges (clerical)
If cnf....min charges (clerical) /before 48 hrs
.....25% of your fare/ from less than 48 hrs, upto 06 hrs of dep of the train.
......50%...
more... of your fare/ less than 06 hrs of dep to +2 hrs after dep of train
......no refund/ after more than 02 hrs after dep of the train.