Source: As worded by Indian Railways, Government of India

1. Where the ticket issuing and journey commencing stations are the same and in cases where they are different (like return/onward tickets), the ticket should be surrendered at the journey commencing station within the following time limits:

   Distance of your journey	Time limit for cancellation(After the scheduled departure of the train
   Up to 200 Km	3 Hours
   201 to 500 Km	6 Hours
   Over 500 Km	12 Hours

2. If the ticket has been issued for travel from some other stations, refund can be obtained at the ticket issuing station before the train departs.
3. Refund can also be obtained from a station other than the ticket issuing and journey commencing stations. In such cases, the ticket should be surrendered during working hours, before the preparation of Reservation Chart. Refund will be admissible subject to verification.

For trains departing between 21.00 hours and 06.00 hours, you can get a refund either within the prescribed time limits or within four hours of opening of the Reservation Office, whichever is later.