As reported on Thai visa
https://www.thaivisa.com/forum/topic...r-us-citizens/
..be aware that the Chiang Mai Thai Immigration office is now requiring proof of income when applying for Extension of Stay ...the retirement visa. They no longer SOLELY accept the Affidavit of Income notarized letter from US Embassy or others.

"Leave it up to Immigration here in Chiang Mai to make it harder for a U.S. Citizen to get or re-apply for a retirement visa. Yesterday afternoon they up and changed the rules for showing proof of income. How besides that $50 rip off form from the U.S. Consulate you have to show where the money came from. You must provide poof of that money. In typical Thai fashion there was no prior notice to anyone. On Monday it was the normal procedure and those at Immigration early on Tuesday had no problem but then, Bam, the rules changed. Guys were caught at Promenada without that proof and were turned away. Needless to say there was quite a lot of really piss..ed off people. I found about this only two hours ago when I went to Assist Thai Visa to begin my renewal process. They never received any prior warning from Immigration and could only tell me what was now required. In my case I have to provide bank statements showing money deposited monthly into to account"

Tod Daniels is an expat expert on Immigration issues in Thailand...group is Thai visa advice.
Tod posted this in reply....

"And at this time that is ONLY in Chiang Mai, not at any other immigration office.

Be advised that if you're using the affidavit of income from abroad letter from your consulate in Chiang Mai that you take proof with you to show the amount on the letter is backed up by something.

So in an effort NOT to start a sh*t-storm of conjecture or speculation of what is or isn't going to happen, I'm gonna close commenting on it."

Tj