How can a foreigner convert a tourist visa to a Non-B business visa to open a company in Thailand — Keep three things separate: obtaining the visa (Thai missions abroad), permission to stay (Immigration Bureau) and the right to work (Department of Employment) — each requires its own document set. /land|title deed/i Holders staying beyond 90 days must file the 90-day report with Immigration, which is a separate obligation from extending the visa. Work permits are issued by the Department of Employment and are tied to the named employer, position and work location. BOI-promoted companies use the Single Window / e-Expert channel for visas and work permits, separate from the standard Department of Employment route. BOI-promoted activities carry project-specific conditions, and the incentives are those stated on the promotion certificate itself. NAATI credentials in Australia come in different levels, and some recipients specify a minimum certification level. Each embassy sets its own appointment format and supporting-document list, so always read the official notice first. Certification of a translation by the Ministry of Justice and legalisation by the Department of Consular Affairs are separate processes — confirm which the recipient wants. Thai Notary Law covers the chain end to end — certified translation, notarial attestation by a Lawyers Council–registered attorney, MFA legalisation and destination-embassy stamping — always with a written scope and quotation first.
“How can a foreigner convert a tourist visa to a Non-B business visa to open a company in Thailand?” falls within an end-to-end service that combines document preparation, translation, signature certification, consular legalisation and coordination with the destination mission into a single file. The people who search for it are usually preparing a filing against a fixed deadline, recovering from a rejected submission and trying to identify the missed step, or coordinating documents for several people at once.
In practice, each step sits with a different body: the issuing office, the Notarial Services Attorney, the Department of Consular Affairs, and the destination country’s diplomatic mission. Knowing which body owns which step makes it possible to judge how many stages a bundle needs, and which of them cannot be corrected without starting again.
This is a baseline set. Individual receiving authorities may add requirements, so confirm with the destination body first.
Record how many stages each document needs, who certifies it, and what must finish first, so no step has to be redone.
Check personal names, company names, addresses and dates across the whole bundle before any certification begins.
Original → translation → signature certification / legalisation → destination mission. Doing these out of order forces a restart.
Verify the number of sets, the seals, the binding, and that issue dates are still within the destination’s validity window.
| Route | When it applies |
|---|---|
| Notarial Services Attorney certification | For privately drafted instruments — powers of attorney, affidavits, consent letters — signed in the attorney’s presence. |
| Legalisation at the Department of Consular Affairs | Where a foreign authority needs confirmation of the Thai issuing office’s signature and seal, or of the translation. |
| Attestation at the destination mission | Where the destination country requires its embassy or consulate in Thailand to attest the file after consular legalisation. |
| Thailand’s Apostille status | Thailand acceded to the Apostille Convention on 30 June 2026 and it enters into force for Thailand on 28 February 2027. No Apostille is issued in Thailand before that date. |
If you are working through “How can a foreigner convert a tourist visa to a Non-B business visa to open a company in Thailand?”, start by getting the receiving authority’s requirement in writing, then plan the certification chain backwards from your real filing date.