ATTENTION ALL MEMBERS:
ALL Immigration offices in thailand will be closed on Monday the 26th of February.
Borders are open like normal
Remember IF you have a stamp that expires a day the immigration office is closed (weekends or holidays) and you go the very next day they're open you can get your extension like normal, you will not be charged the overstay fine but you will get an overstay stamp in your passport that says "Overstay xxx days fine waived due to closure"
TLDR : Answer Summary
All immigration offices in Thailand will be closed on February 26th. However, borders remain open. If your visa stamp expires while the office is closed, you can still get an extension without paying an overstay fine the following day, although you will receive an overstay stamp in your passport.