Originally Posted by
SKT-DK
There has always been the requirement to have a return (or onwards) flight to be eligible to enter Thailand, however in my 20+ years of coming and going, I have never been asked to show it even once. So as long as you have something showing that you intend to leave the country before your eligible stay period is up, you should be fine - also with changes to the itinerary post-entry.
if you have no visa and enter on a visa examption, then there is quite a possibility, that you have to show the return ticket when checking in to your flight to Thailand (happened to me a couple of times when I entered on visa exemption)
but I had never ever to show a return ticket at the arrival in Thailand
If you have a visa, you do not need to have a return ticket