Tatkal ticket booking for Indian Railways starts one day in advance excluding the day of journey from the train originating station. The specific start times are:

• For AC classes (such as 1A, 2A, 3A, Chair Car, Executive Chair Car, and AC-3 Economy), Tatkal booking opens at 10:00 AM.
• For Non-AC classes (such as Sleeper, First Class, and Second Seating), Tatkal booking opens at 11:00 AM.

These timings are strictly followed and apply to both online and counter bookings. The Tatkal booking window is open for about 30 minutes to secure tickets at short notice.