Yes you need a Thai bank account and need to show 800,000 bht each year or bht per month for proof of supporting yourself or 400,000 bht per year if you are married. The retirement funds need to be in a Thai bank at least 3 months before you renew your yearly visa. I strongly suggest that you use a agency as you only need to get one thing wrong on the documentation and it will be rejected. I've just completed mine with Onestop Service at the bottom of Soi 6. The guys name is Mark and this service is excellent. Please don't listen to some people who think they know what their talking about, because everybody isn't an expert. I completed my retirement visa, bike and car licence all at the same time. It will cost you but it will save you the heartache of it all going down the pan.