What do I need to enroll in a Thai language school in Chiang Mai, and how can I change my visa for long-term study?

Better to ask the schools directly ,,,they will give you an up to date information of what is expected from you and what the immigration requires …sorry but theres a lot of misinformation on here about length of study ,,,like previous aspects about the education visa when there was clamp downs regarding age of study ,period of time etcetc ,,so ask the schools directly …the schools at pantip plaza will answer all your questions directly .good luck

i went to ask about this...i aint cheap....and i have taught myself basic thai by putting myself in thai society

I don’t know about studying for four years, but I think TSL has a program with several months of language classes (maybe six?) and a whole bunch of cultural activities, that qualifies for the five-year DTV visa. So, that’d let you *stay* for five years (or, technically, multiple 180-day visits — you’d still have to leave and reenter from time to time), but I’m not sure any of the language schools have a four year curriculum for formal studying.

I think the program is 29K or 39K, plus an extra 10K for the visa.

TSL Language School is amazing

Chaing Mai University has Thai Language course. Only 2 years tho.

That's very ambitious. You may want to look around because in general none have 4 year courses for beginner Thai speakers. New Stamford and We learn Thai are good but message if you want other options for longer term stay in Chiang Mai.

Check out Chula University if you serious about a 4 year program. Costs are quite a bit so hope you got deep pockets

An Education Visa for studying Thai language at a language school is considered informal education. You can only do that for a maximum of 2 years.

Only a university can do more than that.