just checked at the immigration website, no mention of the letter from embassy, if you have the letter you don't need the prove any income in the bank that's the way I do it....... In the case of marriage to a Thai woman, the alien husband must earn an average annual income of no less than Baht 40,000 per month or must have no less than Baht 400,000 in a bank account in Thailand for the past two months to cover expenses for one year.