Is it necessary to have both 800,000 Baht in the bank and 65,000 Baht monthly income for a Thai retirement visa, or can I use just one of these requirements?

Either ONE of them!

I think there was comment on you tube recently about extension of visa needing a proof of living expenses as well. In other words, if you have 800,000 in the bank you cannot touch it so what are you living on? And that means monthly bank book entries or else you have to get a letter from the bank to prove that you are receiving funds from overseas for living expenses. Don’t know if having extra funds already in Thailand for living expenses counts. Probably does. But this is a new wrinkle that has been discussed.

Either. And in many provinces, a combination of the 2 equaling those sums

Either one

One or the other. Easier to have 800,000 BHT in your Thai bank account. 2 months before and 3 months after. Minimum balance 400,000 BHT. More work the other way but possible

800,000 in the bank for at least three months. I find this easy enough, just have to update bank book, far less paper work.

In any number of immigration offices - it doesn't matter what the actual Police Orders say - they do what they want to do. And there is nothing the average guy can do about it without making a permanent enemy of the I/O or the whole fricken office.

There are three ways to meet the proof of funds to get a "retirement visa" inside thailand.

1 - All banked money method; <- bank 800K baht in a thai bank account in your name only for 2 months before you apply for your yearly extension. Keep the money in the account for 3 months after the extension is granted and then don't let the balance go below 400K baht the rest of the year

2 - Monthly income method <- get an affidavit of income from abroad notary paper from your consulate here in Thailand if you can (NOTE: the US, UK and Australian consulates no longer issue them) OR transfer in to a thai bank account in your name only a minimum of 65K baht a month from abroad, each month, every month for the preceding 12 months before you apply for your extension.

3 - Combination method <- use a combination of banked money (seasoning requirements are in effect) and monthly income to hit a total of 800K baht for the year

This image is the combo method spelled out in the currently in effect police order

Cannot mix and match at Khon Kaen immigration. I asked the question directly just over a year ago.

Either one or the other. You can also mix and match, 400k plus 33k a month.