Every non Thai citizen needs a work permit to legally work in Thailand. By law, it is essential to obtain a work permit even for upaid and volunteer work.
A work permit has to be sponsored by the Thai company planning to hire the foreigner. The hiring company needs to meet certain conditions like - registered capital, number of Thai employees etc. It is not possible for an individual to apply for and obtain a work permit on their own.
Due to the stringent conditions for obtaining a work permit, Thai companies prefer to hire locals over foreigners. Most legal foreign workers in Thailand are either experienced managers or specialist workers (IT Professionals etc). A large number of native English speakers also work as English teachers. There is also a large under ground foreign work force working illegally on tourist and other visas.
Working without a proper visa and permit is not only illegal, it also leaves you open to exploitation from unscruplous employers. Its generally not possible to go to court against an employer if you do not posses a work permit.
As per Thai law, an Indian citizen must be paid a salary of at least 45,000 THB to obtain a 1 year work visa extension.
It is possible to setup your own Thai company and sponsor your work permit and be self employed. However, it is a costly process and the lawyer and other Government fees can be quite substantial.
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