Not sure if this will be of interest to anyone,was at Udonthani immigration today to renew extension based on marriage, I had renewed my passport in August 2023 and was updated by Udon immigration then, today submitted all the required paperwork, were I was asked for my old passport which I didn't have with so my wife went home to pick up ,they then copied all of the pages in my old passport and added to my paperwork for my application for extension,I was totally unaware I was required to supply copies of my old passport on top of my new passport, not sure if this the same at all immigration offices in the country, just a heads up for anyone applying for a extension soon.
TLDR : Answer Summary
A user shared their experience renewing their marriage-based visa extension at Udonthani immigration. They noted that they needed to provide copies of their old passport in addition to their new passport, which they were unaware of. This requirement may not be consistent across all immigration offices in Thailand.
