I am currently on business visa, but I'd like to switch to retirement visa. According to my solicitor, i have to cancel the company and work permit, then leave the country, then apply for retirement visa when re-entering on a tourist visa.

I am not really convinced this is true, does anyone know if there is a way to do it without leaving Thailand ? And if I cancel the business visa, does it mean that the next day I'm on overstay ?

Do you have a 90 day entry from a non-b visa or a extension of stay based upon working issued by immigration.

If on a extension of stay you can change the reason for your extension from working to retirement without leaving the country.

You will need a termination letter from your employer dated on after the day you apply for the new extension to cancel your existing extension.

You will need 800k baht in the bank for 2 months or proof of 65k baht income on the day your apply.

Thanks @ubonjoe for the quick reply, I think that sounds right.