I stopped paying Part-B 15 years ago, figuring as OP pointed out, it did me no good whatsoever in Thailand. Just before Covid, I decided to go back to the US and have knee-replacement surgery, both knees. I discovered that without part-B, no hospital or practice would touch me. Basically, the lines between A and B have become so intertwined and interdependent that with any kind of complicated surgery, you can't have one without the other. I discovered this too late. Nothing I can do about it. By the time I realized my mistake, the cost of getting back in was more than I could handle. OP. It's deep and boring but really educate yourself about various options available to you. I have a friend living full time in Thailand who enrolled and paid for some kind of Medicare Advantage package and it has paid for every medical need he has had in Thailand for the last 10 years. Sorry, I do not know which plan it was.