Originally Posted by
JohnnyRockets
How would they know who to charge $20. And on what grounds, since you are not flying out but just transiting.
Anyway, I think if you get your onward BP from the transit desk, don't head up but go straight to immigrations. I believe if they don't issue you a new BP landside they wouldn't know you are due tax if it even is a thing.
Once you go landside and try to re-enter the transit you will become liable to pay the THB 700 thai dep. tax. even if you are in transit only. You have to remain airside in order not to incur the dep. tax.
If the immigration officer is doing his/her job properly, it will be noticed that your BP has been issued by airside transit desk or elsewhere and you will be asked to go back to check-in to get a new BP. You will not get a new BP at check-in without paying the dep. tax.
There has been numerous post in this forum that often it is possible to re-enter the transit area without getting caught/without anyone noticing that your BP has been issued elsewhere than landside BKK. I believe it is what you call "a hit or miss"