All foreigners intending to conduct business, work, or undertake investment activities in Thailand must obtain a Non-Immigrant Business Visa from a Royal Thai Embassy or Consulate outside of Thailand, prior entering in the country.
This type of visa is of special importance, being the only visa for foreigners temporarily staying in the kingdom that entitles them to apply for a work permit and long-term extension of stay in the kingdom as necessary, as well as allowing the holder to apply for permanent residence in Thailand.
Before issuing the Non-B visa, most of the Thai Embassies and Consulates require a letter from the Labor Department, confirming that the requirements for obtaining a work permit are fulfilled.
The initial Non-Immigrant Business Visa issued aboard is generally valid for 90 days and is a single-entry visa.
Without a work permit, a Non-B visa only permits the holder to explore business opportunities (e.g. attend business meetings, trade shows and conferences or Board of Directors meeting), as long as such activities are merely of temporary in nature. They are not allowed to work in Thailand and for all other types of activities, including sales calls, conducting conferences or seminars, non-profit, and charity work, they must obtain a work permit.