, their list of requirements doesn't say. My friend was asked to leave Thailand in 7 days when he didn't have the money in his account. This way he learned about secret requirements...
, Prachin Immigration might ask ppl on marriage extension to show the 400,000 THB when "getting" the extension, i.e. they don't approve it if you do not have the 400,000 THB in your account at this point in time. It is no fixed rule and probably their own rule...