I have an ED visa, if I cross the Mae Sai border for a day trip do I still need a re-entry permit or is there some exception?
TLDR : Answer Summary
If you hold a single entry ED visa and plan to cross the Mae Sai border into Myanmar for a day trip, you will need to obtain a re-entry permit. This is because crossing the border will terminate your current stay in Thailand. There was previously a system allowing for a "VIP pass" that didn't require a stamp, but that system is no longer in place. Any status other than a multiple entry visa requires a re-entry permit to maintain your stay.