This is one of the most common questions I am asked, your friend is correct a non-immigrant visa multiple entry issued by a Thai consulate outside of Thailand means that for the duration of the one year visa you must cross a border every 90 days, the most common way is to go on a Cambodian visa run which will automatically give you a further 90 days, this must not be confused a one year extension visa which was awarded to you by a Thai Immigration Officer within Thailand i.e. retirement visa, business visa you can report to an Immigration office every 90 days.
I have a non-immigrant o type visa one year multiple entries issued from a Thai consulate in the U.K. I presumed I only had to go to a Thai Immigration office every 90 days and report were I was residing, but a close friend told me I have to leave every 90 days can you confirm this?
by Darren McGarry | Thai Visas