TL;DR:Obtain a Non‑Immigrant B visa from a Thai embassy, get a work permit from the Ministry of Labour, then extend your visa at Immigration; working without a permit is illegal.
To work legally in Thailand start with a Non‑Immigrant B visa (apply at a Royal Thai embassy/consulate) and then obtain a Thai work permit through the Ministry of Labour. Typical requirements: a visa application, passport (6+ months), recent photos, a letter of employment or contract, the hiring company’s registration and shareholder documents, proof of qualifications, and company financials. After the work permit is issued (usually processed in about 7–10 business days in Bangkok), use it to extend your Non‑Immigrant B stay at Immigration to an annual extension; renew the work permit and extension yearly while employed. Working without a valid permit is illegal and risks fines, deportation, and blacklisting. For BOI‑promoted companies or SMART/LTR/other special visas the process and documents differ and may be faster—check the issuing embassy, the Thai Ministry of Foreign Affairs, and the Ministry of Labour for exact forms and up‑to‑date rules (official sites: mfa.go.th; labour.go.th).
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