What should I do about my 1-day overstay in Thailand?

The individual has an overstay of one day on their Thai visa, with their extension ending on March 26 and a flight on March 27. Comments suggest that the overstay fines are typically 500 baht per day but are often waived for just one day. Advice includes smiling and explaining the situation at immigration, and it's generally considered acceptable as long as the overstay does not exceed 24 hours. It is recommended to deal with immigration on March 26, before their flight.