With the rules for Tatkal tickets changed, we mentioned earlier that there will be no refund if a confirmed tatkal ticket is cancelled. But, there will also be instances where the ticket will still be in waitlist even after the chart is prepared. As you may know, a waitlisted ticket will not be eligible for travel.
In such cases, if the ticket is booked online through IRCTC, complete refund will be made (minus e-service charge, depending on the class of ticket) automatically by the IRCTC system. This generally happens with in 48 hours from the time of chart preparation. The refund would be credited to your bank account or your credit card, which ever you used to book you ticket.
In case the tatkal ticket is booked offline, you may visit the same reservation counter (or any counter in fact) with your ticket and complete refund will be made minus a small clerical charge.