It used to be a requirement for Bangkok immigration that, after a retirement visa extension, we had to keep our 800000 baht in the bank account for 2 months then could drain it down to a minimum of 400000 baht until 2 months before the next extension when it had to be increased to 800000 baht again. Is this still the case for Bangkok immigration?

Yes for the permission to extend stay based on retirement.

10 minutes ago, Card said:

It used to be a requirement for Bangkok immigration that, after a retirement visa extension, we had to keep our 800000 baht in the bank account for 2 months then could drain it down to a minimum of 400000 baht until 2 months before the next extension

Required to maintain 800k for THREE months after extension granted then not below 400k and back up to 800k for TWO months prior to date of next application for extension. 

Can't speak to what Bangkok Immigration requires but I've always understood that the requirements (certainly in Chiangmai) were the 800k had to be in the account for 2 months prior to the application date (meaning date you get your annual extension, not the date your new annual extension starts), for 3 months after that application date, and 400k for all other times.

Edit:  Posted this at same time as DrJack.

Just now, CMBob said:

,...... for 3 months after that application date, and 400k for all other times.

It's 3 months after application at all immigration offices and as you outlined and 2 months prior.

 

There are couple of offices requiring 3 months prior.