Is it ok to take my son from Bangkok to Mae sot without a valid visa in his passport? He was born here 7 months ago, and before we leave for Europe for good in early april his grandparents would like to see him. They are from Burma so can only go to Mae sot, meaning that we have to fly up there to meet them.

I have not bothered with a visa for him since we planned all along to leave now in april, so if the least doubt I will not take him there.

Bus is not an option, we fly up there or we stay home

Since your child was born here there is no need for a visa. Only if they were to leave and re-enter the country would they need a visa.

When you travel within the country just have their birth certificate with you in case asked for. Airlines will ask for it.

Thanks ubonjoe, as always you answer fast and sometimes what I want to hear

Same when leaving the country for the first time. Show immigration the birth certificate (original) and they know why there is no immigration record of your child and allow him to leave without any problems.