Thanks for the information.

I received a 90 tourist visa for myself and 9 y.o. daughter from the Thai embassy in Los Angeles and purchased round trip flights (Los Angeles, BKK and return to LA, we are US citizens) that from arrival to departure will be 90 days. Upon arrival in Bangkok received a 60 day permit. To file for a 30 day extension:

Do it at the airport immigration office?

Do it on the 60th day?

Can I file the forms (myself and daughter), pay the fees and obtain the 30 days at the airport immigration office on the same day?

Thanks

Do it about a week before your permitted to stay until stamp - it starts when that ends so you lose nothing. It normally only takes an hour or so. Have current 4x6cm photos for application (TM.7) form, copy of passport/entry stamp and departure card and 1,900 baht fee(s). Also have outbound tickets in case they want to see them.

What airport immigration office? Bangkok is currently closed until end of high season. In Bangkok go to Immigration Hqs at Soi Suan Phlu (off South Sathorn Road). You can do at any Immigration office if not in Bangkok.