I already said this in this forum and some people said that I was very wrong 😂, an extension is 10.000 thb not 1900 as many though, if not it would be very different price compared to the other visas available.
Mate I got a letter from the HMRC , they returned me the tax from the last two years, and I paid it in Thailand the tax amount Thailand required me to pay (because I live here the whole year), don't tell me that is wrong as I did with HMRC and with a legal advisor 🤣 (if you think it is wrong, ask HRMC, I am not the one who will explain you).
yes you right, as I said, ask a tax advisor better , the rule is only for countries with double taxation treatments with Thailand (UK has one, Spain, and many countries in Europe, no idea about US).