I left Thailand in 2001 expecting to return in a year. Unfortunately, that didn't happen and I didn't use the account again until 2005. Updated my passbook in 2005 and noticed I had around 1,500 baht in it which was more than I thought would be in it. Old ATM debit card had expired but I got a new one. Everything went very smoothly. This was years ago so maybe some of the banking rules have changed.