the RTE London website says 3 months so, as they handle applications, I’m going by that. You could always contact them to check everything as I’ve been told they don’t actually enforce the insurance requirement even though it’s on the website.
It’s been a requirement for a while but if it’s a Non O for being over 50 then it’s either proof of pension OR the 10k for 3 months not both. I recently got a Non O and used an occupational pension.
in that case you can leave and re-enter as many times as you want up to next May as long as you get a re-entry permit from Immigration before you leave. You can get a Single or a Multiple depending on your plans. You need to make sure you are in Thailand next May for the next annual extension.
FYI the 90 day visits to immigration have nothing to do with your visa or staying in the country. It’s just a requirement for all foreigners to report their address to immigration every 90 days, even if they haven’t changed address.
When you leave the country the 90 days re-sets so you’ll have to report 3 months after your arrival.
You should also report within 24 hours of getting back to Thailand (though some immigration offices tell you it’s not needed)