-Non-Immigrant-Visa-%22O-A%22-(Long-Stay).html A copy of bank statement showing a deposit of the amount *equal to* and not less than 800,000 Baht or an income certificate (an original copy) with a monthly income of not less than 65,000 Baht, or a deposit account plus a monthly income totalling not less than 800,000 Baht.
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.