How do I obtain a Non-O A criminal background check and medical verification in Bangkok as an American expat?

Note: The second option Tod listed to meet the financial requirements to apply for a Non Immigrant O Visa is the Income Method. You just need to have monthly income from outside Thailand - usually one's home country. Then go to your own country's Embassy in Bkk - sign an Income Affidavit (Embassy Letter) swearing that you gave this income. For Americans there is no proof required - just the sworn statement. To get this Form go to the American Embassy website (consular services I think) Make an Appointment on line and download the affidavit form (it can be filled in on line). Fill it out but don't sign it until on the presence of the Embassy officer. It cost $50 or Thai Baht Equivalent. The website tells you what they consider the exchange rate to be for the fee. You state your income in US Dollars. With the Dollar losing ground lately against the Baht it is best to wait until you are at the Emassy to fill that it. And Best to stare a monthly income amount in your favor against future exchange loses as the form is good for 6 months. You include this raised seal stamped Income Affidavit in your Non Imm O application. Don't add proof documents - the Affidavit is enough. When applying for the Non O 90 days take the original but don't let them keep it because you need it to apply for the one year Extension of Stay which will come up 45 days or so after getting the Non O awarded.

Okay, I think we're confusing a couple things which are commonly called "retirement visas"

First is a year-long multi-entry Non-Immigrant Type O-A (Longstay) visa. You CANNOT get this visa inside of thailand, period, end of story.

You get from a thai consulate in your country before you wing your way here. It requires a background check, a medical certificate and proof you have the equivalent of 800K baht in a bank in your country.

The other 'retirement visa' is where you come here, apply for a 90 day Non-Immigrant Type O <- (note the lack of the A after it) visa and then apply for a yearly extension of stay after that. It requires NO medical certificate, no background check and you meet the financial requirements by banking 800K in an account in your name for 60 days prior to your yearly extension application, using a notarized statement from your consulate stating you get 65K baht in income from abroad OR by using a combination of banked money and income to hit the 800K baht per year.

If you have pensions of more than baht a month you do not need 800k in the bank. You can mix and match too. Ie 35k/400k

You only need a background check if applying in the USA and then it can be from your local police. Unless of course things have changed.

You do not need criminal background check if you apply extension based retirement.