Most of the time, foreigners who enter legally will enter as a tourist visa and change the type of visa to a work visa or another type of visa later.
You can apply for a change of visa type but it depends on the reason for the foreigner. It is important that the foreigner has to hold a Tourist Visa or Transit Visa only, and the previous visa must not expire to change the visa type.
Currently, Thailand has different types of visas to meet the needs and qualifications of each business person that includes Business Visa types B, B-A, and Investment and Business IB. Those who hold this kind of visa and want to work in Thailand must obtain a work permit first.
Companies in Thailand all need foreigners with knowledge and interesting ability to make their company grow and develop in a better way than before. However, to get foreigners to work, many steps must do especially indispensable things are obtaining a visa and applying for a work permit.