What is the process for applying for a marriage extension visa at Chaengwattana in Thailand?

Report on my trip to CW yesterday to apply for my second stay extension based on marriage to a Thai citizen.

Two weeks prior my wife went to Huay Kwang District office to obtain an updated copy of our marriage certificate ( KR2). Easy to do. She just had to show her ID card and a copy of our original certificate. And pay 20 baht per copy of course.

Went to Bangkok Bank in the morning before going to CW for my 2pm appointment. No problem to obtain the bank letter or statement. Didn’t have to fill out any forms committing to keep funds in my account for any period of time. I had kept a balance over 400k for more than 4 months prior anyway but it wasn’t mentioned.

Went to CW for 2pm appointment and was finished and out of the door by 3pm. Went like clockwork. All discussions were between my wife and the IO in Thai and the IO only comment to me was to recommend that I get a new passport before applying next year as my passport expires next September. Back in 21 days to get the extension inked in. Note that IO did not ask for the updated KR2. At the end of the process she took a photo of my wife and I jointly holding up a sign in Thai that my wife said it stated in Thai that we are married so that may have been the necessary confirmation that we are still married. IO stated that my wife could come alone on 15 August to get my extension inked in ( having observed that my mobility isn’t good) but confirmed that I would have to attend in person if I wanted to apply for a RE permit. She suggested that I apply for the RE permit at the airport when I leave which sounds like a plan to me.

In conclusion meticulous preparation paid off and I am attaching my homemade check list in case it helps others. Note for the family photos I provided 6 photos printed 2 per page directly onto glossy photo paper with captions below and she was quite happy with them.