Marriage Visa: Is it required that the 400K Baht needs to be sent from a foreign bank, and do you need a certificate from bank that the money has been transferred from a foreign account?
How long do I need to wait before I can spend this 400K Baht "after" I've already got the 1 year extension?
TLDR : Answer Summary
For obtaining a Thai marriage visa or extension, it is not necessary for the 400,000 Baht to be transferred from a foreign bank; domestic transfers are acceptable. The funds must be held in a Thai bank account for a minimum of two months prior to applying for the extension. Immediately after receiving the extension, the money can be accessed, although one should maintain the required amount in the account during the visa period and for renewals.