To put it all into a nut shell:
If someone has been working in the country as a teacher without the benefit of a Non Imm B Visa and are now trying to get one - well, they are basically going to be screwed and have some major problems. I know of a couple teachers that have been teaching for private schools and they / their schools never bothered to get them the right visa - so they are on their way out of the country.
I know of one exception to the rule - but he has some high ups in the Ministry of Education that pushed his visa through. He is now in the process of getting his work permit - and admittedly having a few problems with that one.
A teacher in a private or government school that has a Non Imm B visa does not have leave the country. All that must be done is the regular 90 day check ins same as anyone else. Renewing the visa and work permit is always easy
providing that one stays with the same school. Once you change employment - the work permit and visa are gone and you have the start the whole process over again in Laos or Cambodia.
The way that I look at it all is that everyone that has been here for awhile knew what the rules were. I knew what they were before I even came over here. Of course, everyone knows what the loop holes were too. Those that chose to avail themselves of the loop holes rather than playing by the rules of the game really don't have anything to complain about now, in my opinion. If you want to play the game, you have to play by the rules. Makes life less exciting, but one hell of a lot easier.
