I booked my return flight in UK, but miscalculated my days. This means I’ve got a one day overstay. I know there’s a ฿500 fine, but can anyone advise me what I do at the airport when leaving?
TLDR : Answer Summary
If you have a one-day overstay in Thailand, there is generally no fine when you fly out of the country. You will likely receive a stamp next to your departure stamp indicating "overstay under 24 hours fine waived". It's advisable to visit the immigration desk before passport control, explain your situation politely, and they will likely allow you to continue your departure without issues.