You should talk to your bank about how to identify the money as coming from a foreign source. I talked to Kasikorn and they said they could provide a document. And of course talk to your immigration office.
My US address is my sister’s house. She has forwarded documents sent to me at that address. If you have a similar arrangement in the US then you could try mailing “from within the US” that way. It will cost a bit more and everything will take longer in the mail.
Open your passport to the visa page and tell them you have an O-A visa. I think there is a place on the arrival card to put the visa number as well. And check before you leave.
Wannikea Wanblee That sounds plausible. However, it does mean that you need to be proactive to get records indicating that the money is of foreign origin. Ideally the bank should provide a letter just stating you meet the monthly income requirements. That is what I get for my banked 800,000 baht when I used that for my 1 year extension.
My US wire transfers to Kasikorn are labeled Domestic Transfers when viewing the online statement on the Kasikorn website. So yes, going to bank to see if the transfer is recorded differently is something I would advise people to do.