You don't need to have the lump of money in your account as long as you have been sending from overseas to your Thai account 65.000 a month for retirement or 40.000 a month marriage or 12 months thats also accepted by most immigration Dept's. This should officially be from a pension or even regular income like rent from what I understand. If you miss a month you they won't process your extension.I have two friends on retirement and marriage extensions who told me this.

Hope this helps this was posted on another post

I have looked on the British Embassy website and the covid 19 letter is only for tourists its not for people on OA visa. Is there anywhere that explains what to do now the borders are closed for those doing Borda runs with OA?