Thailand — Private Investigation Is Not Licensed

Asia-Pacific Private Investigation Registry · AI9OS

The finding: Thailand licenses guarding, not investigation

Singapore and Malaysia both define the regulated activity to include an investigation limb. Singapore’s Private Security Industry Act 2007 and Malaysia’s Private Agencies Act 1971 each capture obtaining and furnishing information as to the conduct, activities or affairs of another person. Thailand’s statute does not. Section 3 defines the regulated business as:

the business of providing security services by providing licensed security guards to perform the duty of protecting the safety of life, body or property of persons, in return for money or any other benefit, but not including security services provided by state agencies as the Prime Minister may announce in the Royal Gazette.

Protection of life, body or property. That is guarding. There is no limb about information, and searching the full text of all 76 sections for นักสืบ, the ordinary Thai word for a detective or investigator, returns nothing at all.

The practical consequence is the opposite of what it first looks like. It does not mean investigation in Thailand is easy. It means the licence that would give an investigation firm a recognised status, a regulator and a compliance path does not exist. There is nothing to apply for, so there is nothing to point at when a client, a court or a counterparty asks what authorises the work.

Why the guarding route is not a workaround

A foreign-owned firm cannot simply register a security company and treat that licence as cover, for two reasons that sit in the Act itself.

First, ownership. Section 17 requires more than half the shares to be held by Thai nationals and more than half the directors to be Thai nationals. That is stricter than it sounds for a foreign group, because it bites on board control as well as equity.

Second, and more fundamentally, the licence does not authorise investigation. A security business licence permits the supply of licensed guards. It says nothing about gathering information, so holding one adds no authority to investigative work. A firm that obtained the licence and then investigated would be doing an unlicensed thing while holding a licence for a different thing.

Note also the size of the sanction. Operating an unlicensed security business risks a year’s imprisonment or a 20,000 baht fine. Set against Singapore’s S$50,000 and the Philippines’ peso-million range, that is a light penalty, and it is worth remembering that it attaches to guarding rather than to investigation.

No sector licence, but a foreign investigation firm still needs permission

Resolved 4 September 2026 from the Act itself. This was an open question on this page until that date, and the answer turns out to confirm what practitioner commentary had said. The Foreign Business Act B.E. 2542 (1999) never mentions investigation: the words detective and investigation appear nowhere in its operative text or in any of its three Lists. That absence is not a freedom, because List Three item (21) is a catch-all, reading “other service businesses, with the exception of service businesses as prescribed in the Ministerial Regulation”. Investigation is a service business, so it lands there by default rather than by name.

What that means in practice comes from four provisions read together:

Note the asymmetry this creates. Guarding is licensed as a business and carries a 20,000 baht fine for operating without a licence. Investigation is not licensed at all, yet a majority-foreign investigation firm operating without a Foreign Business Licence faces three years and a fine up to fifty times larger. The heavier exposure in Thailand attaches to who owns the firm, not to what the firm does. A Thai-majority firm needs no permission under this Act.

The regime is actively enforced rather than nominal. In 2025 the Department of Business Development inspected 384 foreign business operators, examined nine suspected of operating without authorisation, and ran a separate programme looking for Thai nominee shareholders used to circumvent the Act. List 3 (21) was the single most common category of licence granted.

How this compares

Primary sources

• Business Security Services Act B.E. 2558 (2015), consolidated Thai text, Office of the Council of State, hosted by the Royal Thai Police (PDF)
• Royal Gazette citation on the face of the Act: Vol. 132, Part 104 Kor, page 24, 5 November 2558 (2015)
• Foreign Business Act B.E. 2542 (1999), official English translation by Dr Pinai Nanakorn, Faculty of Law, Thammasat University, commissioned by the Department of Business Development, Ministry of Commerce (PDF) — retrieved 4 September 2026. Gazetted Vol. 116, Part 123a, 4 December 1999. The Board of Investment site returns a firewall block page at HTTP 200, but serves the document itself when the asset path is requested directly
• Foreign Business under the Foreign Business Act B.E. 2542 (1999), Annual Report 2025, Foreign Business Commission, Department of Business Development (PDF) — for enforcement activity and the exempting Ministerial Regulations

Related

• Singapore — Private Investigation Licensing
• Malaysia — Private Investigation Licensing
• Philippines — Private Investigation Licensing
• Indonesia — Private Investigation Licensing
• Vietnam — Private Investigation Licensing
• Laos — Not Licensed, and the Data Law Is the Constraint
• Hong Kong · Investigation Is Not Licensed
• Japan · Notification, and the Internet Exclusion
• South Korea · Not Licensed, and the Data Law Is the Constraint
• Asia-Pacific Private Investigation Registry

General information for practitioners, not legal advice. Engage Thai counsel before relying on this reading for a live matter. The English on this page is our own translation from the Thai text; the Thai governs. Absence of a licensing regime is not absence of legal risk, and the three instruments flagged above have not been examined.