What is the process for extending a Non-O retirement visa in Thailand and is health insurance required?

With such questions it sounds like a good time to get a Visa agent involved to lay out a course of action.

what is Oz???

To answer your question “do you continue to apply for your yearly extension?” the answer is yes, but in between you must report to immigration every 90 days.

In the UK, you do not need 800,000 baht to get a non-O. I have applied for 3 over the last 5 years and have never had more than 40,000 in my bank account. However, you will need 800,000 in a Thai bank account for 2 months before you can apply for your yearly extension, so if you do not have a Thai bank account, it must be the first thing you do. No insurance is necessary for a Non-O visa.

If you don't already have a Thai bank account get the 90 day Non-O before you travel as you won't be able to open a bank account on a tourist visa

Ulrik is 💯 correct. When you apply for the Non O visa in Aus, you can use money in your Aus bank as proof, but when you apply for the 1 year extension in Thailand your 800,000 has to have been in the Thai account for 2 months (I think you know this already, but just confirming). The non O does not have a mandatory insurance requirement. It is the non OA that requires insurance and police checks etc. The only thing that has changed recently is opening a bank account. It used to be possible with a tourist visa, but now you need a long term visa (like the non O) to open an account, so you will be okay. Good luck.

Extension has to be applied every year. For Non O insurance is not required.