What are the requirements for renewing a Non-OA visa in Thailand?

There's the official Bangkok rules, and then there's what actually happens. Requirements often depend upon what province you apply in, and the officer you deal with.

. .would like to add: "To extend an OA you need everything the same as a non-O plus the required insurance" And then, for the extension of stay out of a Non-imm-O/A visa, the insurance needs to be a private Thai Insurance from the so called "tgia list of insurances", as Immigration will not accept a foreign insurance any more

You're not re- newing your visa, you're applying for a 1 year extention of stay. The main criteria are 800k seasoned for 2 months in a Thai bank account and a years health insurance

The best thing you can do if you have a non-OA visa is purchase another year of insurance and then leave Thailand and return just before the end date on the visa you received from the Thai embassy. This will get you stamped into Thailand for another year (or until the end of your insurance).

The advantage of the OA visa is not having to keep money in a Thai bank but at the trade of requiring health insurance. If you try to extend your OA in Thailand you are giving up the advantage yet still required to keep the insurance so it makes no sense.

To extend an OA you need everything the same as a non-O plus the required insurance.

If you want to do in-country extensions then you should get off the non-OA and onto a non-O so you don't have an insurance requirement.

Or you can do what most people on non-OA do and return home every 2 years to get a new one.