How long after a 6-month or 1-year ED visa can my son reapply for another ED visa in Thailand?

After completing a 6-month or 1-year ED visa in Thailand, the duration after which your son can apply for a new ED visa isn't strictly defined. However, he will need to leave Thailand once his current visa expires, and he can typically apply for a new ED visa from outside the country. It’s advisable to check the specific regulations or any waiting period with the Thai immigration office or a reputable visa agency for the most accurate and updated information.