What are the important considerations for retiring in Thailand regarding medical insurance and banking?

heck your local Thai Embassy/Consulate website and look at the requirements for the Non-O (90 days on entry) and Non-OA (12 months on entry) retirement Visas to see which suits you best. Arriving with one of these makes opening a Thai bank account much easier and you will need one within 30 days of arrival if on a Non-O Visa to get your first 12 month extension (unless your Embassy in Bangkok still does the income affidavit). Arriving with no retirement Visa means you need a bank account to apply for the Non-O in country and this route is more difficult/expensive.