I am planning a 90 day stay next year and am about to book flights. I have more than 90 days off work, we need to arrive on a certain day and will want to stay as long as possible due to Songkran. So I want to stay 90 days, but don't want to inadvertently stay 91 days and be sent to the naughty corner.
How does Thai immigration calculate the days you've stayed? Logic tells me if I arrive on Monday and depart on Tuesday I have stayed one day, but that word 'logic'...
Our flight will arrive at 01.00 and we'll depart in the evening anyway, so it is not a stretch to count both arrival and departure days as one day each.
I'd rather cut the trip one day short than stuff around with a border run.
Cheers.