Is it safe to stay in Thailand for 30 days and leave just before midnight on the last day without overstaying my visa exemption?

@อาจารย์ ******

Get an official document from the doctor that you had to stay in quarantine.

@Lai ************

yes, unless things change.

@David *****

this is quite normal, before covid where i could fly to Chiang mai, i many time have 3 or 4 flight and a trip on 24 to 30 hours

@Maxime ********

Chiang Mai airport is the most lay back in all Thailand. I travel through that airport more then 10 times. First, you overstayed by 1 day, not 12 hours, it's counted in days. Second, overstay is 500 baht fine per day, but for a day usually you don't get charged. Do you remember if you got charged and if so, how much? Third, no, you won't have problem when you come back. The stamp you got is a "overstay notice", which tens of thousands of foreigners get every year. I have had several of these stamps in the last 12 years. It's not a problem as long as you overstayed for less then 90 days. Anyone who tell you otherwise is using google at their information.

@Maxime ********

but they are not overstaying. They fly out before midnight of their 30th day