Attention:
Immigration holidays for July:
ALL immigration offices in thailand will be closed the following days
Thursday 10th July
Friday 11th July
Monday 28th July
If your stamp expires on 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 and will not be charged for overstay. But expect long lines.
TLDR : Answer Summary
All immigration offices in Thailand will be closed on July 10th, 11th, and 28th, 2025. If your visa stamp expires on a day that is a weekend or one of these holidays, you can still receive an extension on the next business day without facing overstay penalties, although you should expect longer wait times.