I did the one year extension for my retirement visa at Chiang Mai immigration. There are a number of new documents to be signed now regarding penalties for infractions of immigration laws. One document is in Thai and I can only read Thai very slowly.
I had more than 800,000 Baht in my account, so no problem this year. I asked two immigration officers and a visa service employee about the new rules and all three agreed: After March 1st, 2019 you must keep 400,000 Baht in your account at all times. At a minimum of 90 days before you do your next extension you must have a minimum of 800,000 Baht in your account. You cannot use an aggregate of monthly income and bank balance. Only the money in your account counts.
If the rules as I have stated above are not correct, let me know.