Do I need to maintain 800k THB in my account for 2 or 3 months before applying for my retirement visa extension in Thailand?

Recommendation. Go to the IO and speak with a supervisor, get their name, then proceed with what you are told. Remember TIT, and things can change by the minute or if someone is having a bad hair day. Good luck.

2months for the first time 3months for the rest of the extensions

For simplicity sake, I recommend to park your 800k thb in a separate savings account & don't touch it. It will give you peace of mind & immigration will also see that you can easily afford to live in Thailand. 800k isn't much anyway 🙏 Your question already has been answered by other members.

I have just done this and played it safe. In other words I had the 0 baht in my K bank account 3 months prior to application. I applied using 12 monthly payments of baht into my BB. I had to submit my UK bank statements. I got my stamp without being asked for my K bank statement. Make of that what you will but playing it safe is always a good idea.

You do need to ensure that you have 12 full months of a minimum of 65k each and every month at the time you apply for your next extension, not the date your extension is due.

Okay this is a best practice approach.

You should bring the account back up to 800k 2 months before the next extension EVEN if you are switching to income method.

By doing this you guarantee that you will get an extension IF for some reason they deny the income method.

Any sort of mistake, or what can be interpreted as a mistake could cause you to start all over again.

For the sake of a couple more months this is the safest practice.

So the answer is are you cautious or are you certain you fully are qualifying for the income method?

I've seen extensions denied because of the money not transferred close to the same date every month and some that dropped just a few baht under because of exchange or fees.

Will you have 12 months of 65k transfers completed at the time of your application for your next extension? If you started the transfers at the start of your current extension it could be very tight and mean doing your new application right at the very end of your 12 month stamp leaving you very little recovery time for any extra documentation required.

for your own safety I would say keep the 800,000 THB in your account from up to 2 months before you next application. After you have switched to the 12-months transfers method and been issued the next 1-year extension, you are safe to take the money out

The coming two months is eventually for your next extension if you want to continue to apply based on funds. If you’ve had two months seasoning before and three months after your current extension and and your account hasn’t dropped below 400K baht for twelve months you’ve fulfilled the formal requirements for this specific extension.

If you want to switch to the income metode for your next extension it should be sufficient that you’ve done twelve months consecutive transfers parallel to and since your current extension was issued.