What are the updated requirements for obtaining a Non-O retirement visa in Thailand regarding bank statements?

does siam commercial bank do it in 1day, anybody knows?

Okay, the seasoning of funds for banked money method changed a good while back.

BEFORE you needed to only have the 800K baht in your bank account for 2 months before your FIRST yearly extension based on retirement and then for 3 months for every yearly extension after that,

BUT

When they changed the rules it went to 800K baht in your account for 2 months before you apply for your extension, the funds need to stay in the account for 3 months AFTER you get the extension granted and then the balance can't fall below 400K baht the rest of the year. <- Those are the seasoning rules in effect for yearly extensions based on retirement using banked money method as proof of funds.

IF you're using a regular savings account (not a fixed deposit one) and don't update your bank book every transaction OR at least every month when you do update the bank book all it usually prints is a transaction summary (money in money out since the last update). That's NOT enough information for the immigration office to tell you met the proof of funds. SO they make you go to your bank and get a print out of a year's transaction history.

Most banks can print 6 months of that history on the spot and you have to order the other 6 months which takes about 5 days.

They need to check that the balance has not fallen below the 400k mark for the previous year.