If you are working in Thailand or plan on living and working in Thailand then consider that you need to have a work permit in Thailand. Also note that you are only allowed to work when you have the ‘blue book’ or work permit in your hand. You are not allowed to work until such time that you have the needed paperwork.
There are a number of positions that foreigners are not allowed to hold. These would included but not limited to law, property and agriculture. Most expat lawyers in Thailand are registered at legal consultants and not as lawyers. The very same goes for property estate agents. Work permits over the past 7 years have changed on a number of issues. The first which most recall is that you now have to work at the location stated in your work permit. Before they allowed you a work permit and you could work at 2-3 branches of the same company. The new work permits state where you are allowed to work and you may only work at that single branch of the business. You can have any other branches and locations added and this is what is new in the work permit rules.
Once you have stopped working in Thailand you need to inform the Labour Department within 15 days that you have completed you employment and have handed back your work permit to the Department of Labour. Now here is the last change. Before you could leave the country within 7 days after handing back your work permit to do a visa run and then come back with a 15 day entry stamp from the border. This was then changed to leaving the country the same day which is impossible to do known how far the border is in Thailand. This was again changed to 7 days the last time it was checked so ask at the Thai Immigration what the rule is now again as it is always changing.
One last issue with regards to the work permit. There is no such visa as a work visa in Thailand. They are referring to a business visa which normally is used for you to apply for a work permit in Thailand. That is the purpose of the Thai business visa. The visa gives you no right to work in Thailand only to apply for a work permit.