@Jay ******
The do-it-yourself costs are the same as were in 2018, when I renewed my O Visa at the Chiang Wattana office. At that time, all was neeed was an affidavit from the U.S. Embassy, in which I stated in writing that my monthly income was more than 65k per/month. I paid 1900 Baht for the 12. But in 2019, the law changed, and affidavits from most embassies were no longer accepted by immigration. Reasoning is I guess is that immigration finally caught onto the fact that embassies (except the German Embassy) do not verify income. I knew some retirees who lied on those affidavits about their true income. So now, for 1900 Baht, plus around 3-4k Baht for the multisple entry, you can do yourself, in person at immigration. But if first time applying for the O visa, you'll still need to pay 18k Baht for the conversion from tourist to Non-immigrant 90-day visa. If you have already transferred 800k Baht from your home country, electronically via international wire transfter into your Thai bank account, then you can do on your own for a mere 1,900 Baht plus 3-4k for the multiple entry permit stamp in your passport. Here is the catch 22 that forced me to go to an agent nowadays. If your application is based on monthly income, you will have to present to immigration 12 consecutive Thai bank statements, showing that you have had deposited by international wire trasnfer at least 65k Baht each month. Well, for first time applicants, you don't even have a Thai bank account. In my case, I had an account, but I didn't want to wait in Cambodia or Philippines for 12 months, while I had my pensions going into a my Thai bank account. Rather awkward. That is why, in 2019, I decided not to pursue a Thai extension based on retirement. I could have gone to an agency, but I decided to move to the Philippines at the time. The way this is set up I believe is a major reason most expats have to use an agency. Using an agency brings in more revenue for immigration district offices, that is, unofffdical money that isnt' included in the official accounting books for general revenue record keeping. Baht. The high demand for extensions here in Thailand allows for such policy. People are more willing to pay a higher fee to stay in Thaialand. If the demand wasn't so high, visa agencies would be out of business, and immigration officials would have to live within their government salaries.