I switched from an OA to a 10 year pensioner LTR. A lot of people don’t know where to read about this visa. Here is the link to the Thailand Board of Investment website
The LTR is 50,000 baht for 10 years. Hardly expensive. You may be thinking of the Elite visa which is pretty pricey. While the LTR isn’t expensive to obtain you must have $80,000/ yr passive income to qualify for.
I found immigration in Bangkok to be very organized and professional. They do everything by the book. I did my OA extensions there for 6 years and never had a problem. I found no need for an agent.
You stay 6 months. Then you can extend 6 months in Thailand at the Immigration Department one time. I’m not sure what the Immigration Department is going to ask for an extension.
If you can do it yourself and they want 5k for insurance then that sounds like a bargain compared to an agent. I bought the insurance at Kasikorn. It’s real insurance. A couple of months later I had an accident and Kasikorn paid the 5k promptly.
You become a tax resident in Thailand if you are in Thailand for 180 days. Starting in 2024, money brought into Thailand is taxable. It is hard to say what this means until Jan-Mar when we can see the Thai tax forms. Thailand has dual tax treaties with many countries. For US citizens federal pensions such as Social Security are not taxable in Thailand. You would have to check the tax treaty details for your country.
If you have a pensioner LTR visa then money you bring into Thailand is not taxable.