I actually understand the Thai logic in this. You can only get a year's bank statement up to the previous day to renewal, so in theory you could withdraw money from an ATM taking you below 800k on the morning of renewal without immigration knowing. By insisting on seeing a bank book transaction on the account the same day they know for sure that there is 800k in the bank at the time of extension renewal. Mind you an ATM withdrawal can still be made after the bank book update without it showing in the bank book. So OK, you are right it is illogical...555. Also after extension renewal you can go and withdraw as much as you like but in both instances you would not be able to renew the following year.