How early should I start renewing my retirement visa in Thailand before visiting the USA?

@Joanne ****************

you don't need to switch anything. The extension is basically the same as getting a new one. Just make sure you have the bt800,000 in your Thai bank account before you leave. If it expires there is no penalty when you get a new one. Just make sure you can show that the bt800,000 came from an overseas source, then you are set. I think you are confused about something. When you apply for your year extension, and have all your paperwork in order, mainly your bank paperwork, you get the visa extension on that day you apply. There is no waiting. I think you misunderstood the part about the 45 days. That is how many days before your current visa/extension expires that you can apply for your next extension. It is not how many days you have to wait for it to be approved. If your current retirement visa expires in the beginning of June, then you can apply for your year extension toward the end of April, and you will get it on the same day you apply, as long as all your documents are in order.

I normally apply for mine 6 weeks before the expiration date in Chiang Mai, if I’m going to be away when it’s due I let them know and apply for renewal on return

In Bangkok you can apply for an extension 45 days in advance. You have to be in the country for the extension.