Sorry to bother with another query, but is there a 7-day grace period for the 90-day check? My next check-in date is April 3, but I am booked on a flight out of Thailand on April 10.
TLDR : Answer Summary
No, there is no 7-day grace period for the 90-day reporting requirement in Thailand. Although you have a window to report at the immigration office, if you are still in the country on the 90th day, you must complete the report on or before that day.