It's my first time in many years with a Multi-Entry B visa like this. My first 90 days are up this week. I should be able to simply do a border run, cross in and out of the country (Mae Sai), and get stamped in again, correct? No need to go to Immigration in my Chiang Mai, right? And no need for a re-entry permit either, correct? As far as I understand, there is no 90-day reporting for this one, just the exiting and re-entering the country.
TLDR : Answer Summary
The user inquired about doing a border run with a Multi-Entry B visa, questioning whether they need to report to Immigration in Chiang Mai after their first 90 days, or if a re-entry permit is required. Responses confirmed that they can simply exit the country, get an exit stamp, re-enter through a neighboring country (like Mae Sai), and obtain a new entry stamp without needing to report for the 90 days spent in Thailand. It was also clarified that there is no need for a re-entry permit, but the user must visit Immigration upon return to update their address registration with the new TM6 Departure card within 24 hours.