Since 15 years living here on extension of stay (purpose: retirement) and every year leaving THA for holiday up to three months (Schengen visa for my long time Thai partner). Coming back with re entry permit ... never ever been asked for proof of funds (or anything else) by IO at BKK.
First question of the bank employee will be: have work permit ? (Wrong question) But as Tod explained, there is no reason not to open an account for a foreigner in THA.
Yes ! Visa O A or extension of stay comes with the permit to open bank (savings) account(s) in Thailand. What all the numerous bank employees are telling us since many years (Have work permit ?) is WRONG ! TiT !
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