OVERSTAYING IS ILLEGAL !!! >:(
I think we need to touch on this subject because topics about overstay come up at least once a day.
Plain and simple it is against the law to overstay, period, end of story.
The fine for overstay is 500 baht a day and caps out after 40 days at 20K baht.
The overstay/banning penalties have been in effect since March 20, 2016.
Too many people think it's no big deal and truth be told short overstays are usually no problem and at this time having an overstay stamp in your passport doesn't hurt you when you entering the country again.
The thai consulate in Penang recently started a policy where they will not issue a tourist visa to people who have an overstay stamp in their passport. There is no telling when/if other consulates will start following this policy.
My advice to anyone is DON'T overstay!
TLDR : Answer Summary
Overstaying your visa in Thailand is illegal and can result in significant fines, starting at 500 baht per day and capping at 20,000 baht after 40 days. Since March 2016, these penalties have been enforced, and recent policy changes at the Thai consulate in Penang have begun to deny tourist visas to those with an overstay stamp in their passport. Many community comments emphasize the necessity of respecting immigration laws and the ease of obtaining extensions or leaving the country correctly to avoid fines.
