As of last week, they have returned to the old system whereby you clear immigration at final destination domestically. To see the lines of people covering the domestic immigration in Survanabhumi was a complete mess. I think they implemented it because of security at the outlying domestic airports.

To my knowledge, you can know clear immigration in Chiangmai, U-Tapao and Phuket, any others, please someone help and add them on. When they are going to implement this for all domestic airports I can only hope. The amount of traffic of people in the check in area could be reduced greatly if they would upgrade all the domestic airports. My local one has had a booth for immigration for years with no facility for clearing for about 5 years.