Tatkal tickets can booked at any railway reservation counter or online thru thir party websites. But there are many things one should learn about.
1. Tatkal tickets can be issued just 1 day before the actual date of journey
2. Passengers need to submit the copy of the identitity copy (and to carry out the original) while booking at the reservation counter
3. One can book tatkal tickets from 8:00 A.M. at any railway reservation counter
4. One can book tatkal tickets online via IRCTC.co.in portal from 8:00 A.M. onwards, But it will be very slow.
5. One can book tatkal tickets online thru other third party websites such as yatra, makemytrip, travelguru, cleartrip and few other only from 9:00 A.M.
6. For Example, Rajdhani train starts from Bangalore on Friday evening 8:00 P.M. and reaches Hyderabad on Saturday Morning 7:35 A.M. and then reaches New Delhi on Sunday Morning at 5:50 A.M.
7. Now, If anyone wants to travel from Bangalore to Hyderabad or Bangalore to NewDelhi, He has to book the tatkal tickets on Thursday monring.
8. If anyone wants to travel from Hyderabad to Bangalore, He has to book the tatal tickets on Friday Morning, but not on Thursday. (Even though train starts at Bangalore on Friday). In this case, Since passenger is boarding from a station which is in between the journey. So best thing is to book a ticket from Bangalore to Delhi on Thursday morning and to keep Boarding station as Hyderabad.
9. For Tatkal tickets, minimum extra fare is Rs. 75 and it will be upto Rs. 300 depends on the class of ticket and distance of travel.
Happy Journey !!