Today (14 Mar 2022) I got a new annual extension of stay stamped into my new passport at Roi Et Immigration office. My previous extension expired on 11 Feb 2022. When I submitted the extension application on 10 Jan 2022, the Immigration Officer pointed out that my passport expiration date is 23 Jan 2023. I thanked him for pointing it out and left with the stamp in my passport instructing me to report back to the office on 13 Mar 2022 to get the new extension stamp. In the meantime, I got a new passport with a new expiration date in 2032. When I got the new extension-of-stay stamp today I noticed that it is valid until 23 Jan 2023 which is the expiration date of my "old" now-cancelled passport, which means that I didn't get a full year on the new extension. So this is just a heads-up that if your passport is nearing expiration when you need to apply for a new extension of stay, you may want to get a new passport before you apply for the extension. Also, FYI, they stamped the extension-of-stay stamp in both old and new passports, and I need to present both of them when I apply for the next extension of stay.
TLDR : Answer Summary
The user recently dealt with an issue where their extension of stay was only valid until the expiration date of their old passport. They received an extension stamp in both their old and new passports but noticed that the extension only lasts until January 2023, the old passport's expiration date. They advise getting a new passport before applying for an extension of stay and add that current extensions can be transferred from an old passport to a new one with the appropriate embassy letter.
