I am a 52 year old US citizen in Bangkok. I arrived on November 14th and stayed in Thailand until November 22nd (8 days) then traveled outside the country until November 29th. Now I am back in Thailand and when I arrived on the 29th of November the immigration agent stamped December 20th on my passport (visa on arrival at the airport). I am guessing that he included the 8 days that I was already in Thailand as part of the 30 day visa so he only gave me 22 more days. My question is, if I leave Thailand for Cambodia on or before December 20th and return lets say on December 30th by land (planning to return by bus) will the immigration officer allow me to enter the country and if so how many days will I be getting? I hope that I would be able to stay at least 15 days because I have a flight scheduled to return to the US on January 13th and it is departing from Bangkok.

Please let me know what the Thai laws are or what people who have done this have experienced. I talked to Thai immigration and they only said that I need to extend the visa before the 20th of December at the immigration office for 30 days which costs 1900 baht. He would not answer the question I wrote above. Could I avoid the 1900 baht fee and just leave legally before the visa expires and then return in 10 days and get a new visa for at least 15 days? In the past 6 months I was in Thailand only 1 other time, in July I was here for 14 days, so my total number of days in Thailand since July 1st 2014 will be 45 days.

You should have gotten 30 days at the border on your visa exmept entry. if you want you cna have the stamp corrected at immigration in Bangkok.

When you return you will get a new 30 days, either by land or air, as you are a US national.

Yes, if you do not want to leave for Cambodia and just stay in Thailand you can get a 30 day extension at immigration.

You should of been stamped in for the entire 30 day visa exempt entry (it is not a visa on arrival). The immigration officer probably used the wrong date stamp. You could go to an immigration office and get it corrected.

You will get a 30 day entry at a border crossing because you are from the US (G7 country rule) without a problem.

You should get 30 days every time you enter Thailand.

You can also get 30 days extension at Immigration 1,900 Baht

Thanks everyone who replied. I am happy to hear that!