Judy, I met with the Immigration Office in Ubon Ratchatani last week. They will accept 12 months of UK bank statements proving I meet the
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THB per month requirement.
They said this does not have to be an affidavit from the UK Embassy. That was never a requirement from Thai Immigration, but many ex pats chose to provide it.
As I mentioned before this now academic for me as I am marrying my Thai fiancée in February. The Ubon Immigration Office confirmed that 12 months of UK bank statements confirming I meet the 40,000 THB per month income requirement is all they need. They said for my renewal in one years time I will need to show that this monthly income has been going in to a Thai bank account.
After only 4 months looking at this it is very clear that each Thai Embassy and each Thai Immigration office has their own interpretation of Thai immigration law.
My advise is check with the local Thai Immigration office who will process and issue your visa and only follow their instructions.