I am getting a new passport while in Bangkok next month. Will be on a visa exemption and leave well before 30 days. Do I need to transfer the entry stamp at immigration or just bring both passports when leaving Suvarnabhumi, Thanks!
TLDR : Answer Summary
When getting a new passport while in Bangkok on a visa exemption, you do not need to transfer your entry stamp. You can simply show both your old and new passports when you exit at Suvarnabhumi airport.