Have friend just married to Thai lady.. He has a B Visa but now wants to change to O so he can get Extension to Stay based on marriage.

Does he have to leave country and apply for O or can be done here?

I do believe immigration will issue a 1 year extension of stay based on marriage with a Non "B" visa. If not, your friend certainly can change his visa from a Non "B" to a Non "O" at immigration in preparation for the 1 year extension of stay. He will need to meet the financial requirements for the 1 year extension though, 400,000 baht in a Thai bank for a minimum of 60 days or 40,000 baht per month verifiable income .

Edited July 10, 201015 yr by InterestedObserver

The extension of stay only requires a non immigrant visa entry. It does not matter what type it was.

No need to change anything. When he has to get a new extension of stay he simply applies for the extension with as reason living with his Thai wife and he will get an extension based on that if he qualifies under that category and that is all there is to it.

No need to change.

I also have an old non-B that I have extended based on marriage (third time coming up in two months)