What is the name of the bank letter required for a marriage visa extension in Thailand?

To extend your marriage visa in Thailand, you need a bank letter that serves as proof of funds. This letter is typically referred to as a 'Banking Reference Letter' or 'Guarantee Letter' for immigration purposes. It confirms your status as the account holder, your account number, and your current balance. You can request this letter at your bank, and they should be familiar with what is required. Remember that the letter is only valid for 7 days, so plan accordingly.