I use to provide a source letter as well from both Social Security and pension . This year they said dont need that all they want is a bank statement showing at least 40,000 baht coming in the country every month for the past 12 months . Then a letter from the bank stating these funds are international transfers . This letter must be less than 7 days old . Copy of all pages of the bank book and up date it the morning your going in . Also when you get your statement mark lines showing the deposits. I just did mine last month at the airport . Advise , get all your papers and copies ready , go the day before have them check them . Show up early next morning and drop your papers in the basket you ll save yourself a lot of time .