If a person whose visa expires is stranded in Thailand, will he be detained at the embassy?

The embassy does not care about this. If you are detained for other illegal reasons, you can apply for consular assistance.

After entering Thailand, foreigners should pay attention to the validity period of their visa. According to the current law (implemented after March 2016)

If foreigners overstay, they will be fined 500 baht per day, up to 20,000 baht. In addition, they will be subject to the corresponding re-entry ban. .

The details are as follows:

Those who voluntarily surrender to the Immigration Bureau:

Those who are overdue for more than 90 days and less than 1 year will be prohibited from re-entering within 1 year. (Counted from the date of departure)

Those whose overdue period is 1-3 years will be prohibited from re-entering within 3 years. (Counted from the date of departure)

Those who have overstayed their visa for 3-5 years will be prohibited from re-entering the country within 5 years. (Counting from the date of departure)

Those who have overstayed their visa for more than 5 years will be prohibited from re-entering the country for 10 years. (Counting from the date of departure)

Those caught by the Immigration Bureau:

Those who are overdue for less than 1 year will be prohibited from re-entering for 5 years. (Counting from the date of departure)

Those who are overdue for more than one year will be prohibited from re-entering the country for 10 years.

(Counted from the date of departure)