Unless you are doing 90 day reporting, you will need to go to the Immigration Office in Klong Yai which is near the Cambodian border. This is the main office for this region.
To get to Klong Yai you can take a minivan from Trat Bus Station. It is about 1 hour drive from Trat town.
It is located in the centre of Klong Yai town on a side street near the sea. The location is marked on the map below.
Monday to Friday: 08:30 – 16:30
Saturday & Sunday: Closed
Buddhist and Public Holidays: Closed
Email : firstname.lastname@example.org