On TV forum is a recent report about the extension where the OP had a lengthy chat with one of the immi-officer.
He didn't mention which office it was on purpose, as every office might do it differently.
One thing was, that even those who are doing the 1 year extension before 1st of March, will have keep more than 800k in the bank for the coming 3 month (or 400k for married or the combination). Otherwise the next extension won't be granted. To proof this, one needs to show a bank statement for 12 month at the next extension. It might take the bank several days to produce such a statement, so better talk to your bank ahead of time.
Went to Jomtien today to apply for my retirement extension and the lady there confirmed that I will have to keep my 800k for 3 month longer.
Furthermore the pick-up time for the passport in the morning (10-11am) is currently cancelled (the time on the sign at desk 8 was crossed out), so only pick up time is 2-3 pm.