Will I face repercussions for dropping my retirement visa bank balance below 400,000 baht?

Move to Philippines and you will never have these issues with all Thai regulations and ever changing visa requirements/rules.

Don't worry about it, just go for your extension. The worst can happen is you'd have to go through the renewal again. I'm fairly sure immigration won't hold it against you.

Consult the agent. Prepare 20k+ to fix the problem or leave the country and restart fresh.

I think your house will have to be demolished now

Going through an agency is not 100% ok because they tend to go around the law.

What I would do, is to go directly at the Immigration office and explain your situation to them.

If you are polite with them, they usually try to help, They can easily extend your visa for one month (1900 baht) in order to reach 60 days you need with 800k baht on the bank account.

I don't know exactly you expiring date, but maybe 30 more days can do it.

My extension is granted with a simple letter from the bank, stating that I have 800.000 baht currently in my Thai bank account . 🤷🏻

I miss read your question please disregard the answer I deleted .. Change to an extention based on marrage if you can .

how are you building a home? only locals can by land. thai wife?

you should use an agent to solve that issue

If I'm understanding this correctly you fairly recently got an in country Non-O visa based on being over 50 and then got a 12 month extension of stay for the same reason. To get the 12 month extension of stay you need to have had 800k baht in a Thai bank account in your name for 2 months before you applied for the extension. You then need to have kept that 800k baht in your bank for three full months after obtaining the extension and not drop below 400k baht at any point in the year. The upshot is that you have not abided by the terms on which you were granted the extension of stay and so will likely be refused any further extensions. It's not insurmountable, you would just need to leave, return on a visa exempt/tourist visa and start over again, or get the 90 day Non-O while you are out of the country

Can't drop below 800k for the first 3 months of your extension and 400k for the rest. If you want to extend again it needs to be back up to 800k 2 months before you apply.

Any deviations would mean you'd need to start the process again by applying for a Non Imm O visa.

There's a good chance you will have to apply for a new non-o. If you're next extension isn't until mar-2026, how did you get your extension that would start Mar-2025?

If your next extension date is in March 2026 then it sounds like you just got an extension recently. If that's the case you are not allowed to drop below 800,000 for 3 months after you receive your extension, and then it can NEVER drop below 400,000 baht. If either of those is not met, you will likely be denied your extension next year. They ask for a 12 month bank statement and will review to ensure you met the requirements of the previous year extension, and if you did not they will not let you apply for your new one.

If that's the case, you'll either need to use an agent for the extension next year to bypass the financial requirements or you'll need to leave Thailand and return either visa exempt or get a new non-O visa and return.