Until further notice, Chiang Mai immigration will close (stop letting people in) at 4PM now because of the adjusted bank hours. This includes 90-day reporting drive through, as well.
Please don’t show up at 3:45 to extend long visa or try for COVID-19 extension. Give yourself an hour for each.
TLDR : Answer Summary
Chiang Mai immigration now closes at 4PM due to changes in bank hours, which also affects the 90-day reporting process. It's advised to arrive early, as last-minute arrivals close to the new closing time may not be accommodated.