I have a research engineer here for 3 month training. He has a 90 day visa which expires on the 27th Jan but his flight is on the 1st Feb. I suggested to go to Chianmgai immigration to get a 10-day extension but they (immigration) said it would be easier to go to Mae Sai and get a 30 day VOA (he's Indonesian). Curious why it would be easier? Seems something to do with required paperwork for the extension is complex.

There is not supposed to be extensions of non immigrant 90 day stay but as a rule they have allowed very short 7-10 day normally from my understanding. The fact he is Indonesian may have something to do with it - as might possible new policy to look harder at these short extensions. As might your idea it will be easier for them. Believe it is really an under review period and extension is not granted so probably causes paperwork problems if has to go up chain of command.

There is not supposed to be extensions of non immigrant 90 day stay but as a rule they have allowed very short 7-10 day normally from my understanding.

Thanks for the info lopburi3, will pass the information on. I think the university will drive him up to Mae Sai and give him a couple of days as a tourist in the region. I just assumed 7-10 days extensions were simple.