I went to BKK Bank on Selom RD BKK and the very nice lady who does know about US Social Security set it up she said it would be sent to BKK Bank New York. Then sent to Thailand. A few months ago she called me and told me I needed to contact SS. I forgot to send the yearly form.
Why would you want to use a US Bank if you are leaving the USA? I use Bangkok Bank for all my banking needs. My Social Security is directly deposited to Bangkok Bank. You can save a lot of money by not keeping a US address. Medicare will not pay to Thailand and you can buy good insurance in Thailand. You do have to pay Medicare if you have a US address. You do not have to pay Medicare if you use Thailand as your address. Medical is much less costly here and better than in the USA.
I was never asked by immigration where the money came from That account has much more than 800K. I also have 2 more accounts. Evidently, if we have enough Baht they do not question.