I’ve been taking a LOVELY sabbatical break on the beautiful island of Koh Samui,Thailand for the last few weeks and took my Monzo card with me.
I’ve not had one problem with using it over here, all ATMs I’ve found are willing to accept the card - this includes the well known yellow ATMs and also the Thailand bank (green ATMS). I have been charged 200 bhat for each transaction and as the island is very cash merchant orientated I would advise to try limiting the amount of times you need to withdraw.
I brought a Thai Sim on arrival (if your travelling here in the airport they have the cheapest 400 bhat for 30 days unlimited internet sim) and I’m literally gobsmacked at how quickly the app notifies me of any spending, I’m pretty sure the app tells me before the cash comes out of the machine!
Will continue using and update you with any ATMs I find that don’t charge at all - haven’t found a citibank ATM I hear these are free!