Foreign investment in domestic land transportation services is subject to approval under List 2 of the Foreign Business Act, and all other land transportation services and auxiliary services are subject to approval under List 3 of the FBA. 
[In the OECD FDIRRI, it is assumed that all other surface transport services activities (including international road transportation) are also subject to approval under list 3 of the FBA (parag. 21). It is considered that all services sectors, which are not explicilty excluded from FBA purview nor explicitly subjected to minority foreign equity holdings under sector-specific legislation nor disqualified from FBA screening under such legislation, are subject to discriminatory screening as provided in the FBA].
"Section 4
In this Act, “foreigner” means:
1. a natural person who is not of Thai nationality;
2. a juristic person not registered in Thailand;
3. a juristic person registered in Thailand, being of the following descriptions: 
a. being a juristic person at least one half of capital shares of which are held by persons under (1) or (2) or a juristic person in which investment has been placed by the persons under (1) or (2) in the amount at least equivalent to one half of the total capital thereof;
b. being a limited partnership or a registered ordinary partnership the managing partner or the manager of which is the person under (1);
4. a juristic person registered in Thailand at least one half of the capital shares of which are held by persons under (1), (2) or (3) or a juristic person in which investment has been placed by the persons under (1), (2) or (3) in the amount at least equivalent to one half of the total capital thereof; [...]
[...]
Section 8
Subject to section 6, section 7, section 10 and section 12:
1. no foreigner may operate such businesses stricto sensu not permissible to foreigners by special reason, as prescribed in List One;
2. no foreigner may operate such businesses related to national safety or security, businesses having impacts on arts, culture, traditions, customs and folklore handicrafts or businesses having impacts on natural resources or the environment, as prescribed in List Two, unless upon obtaining permission from the Minister with the approval of the Council of Ministers;
3. no foreigner may operate such businesses in respect of which Thai nationals are not yet ready to compete with foreigners, as prescribed in List Three, unless upon obtaining permission from the Director-General with the approval of the Commission.
[...]
Section 15
A foreigner which is a juristic person may operate any business specified in List Two only where not less than forty percent of its shares are held by Thai nationals or juristic persons which are not foreigners under this Act, save that, where there is a reasonable cause, the Minister with the approval of the Council of Ministers may reduce the proportion in this matter, provided that the required shareholding must not be less than twenty five percent and that not less than two-fifths of the total number of its directors must be Thai nationals.
[...]
Annex [...]
List two. Businesses related to national safety or security or having impacts on arts, culture, traditions, customs and folklore handicrafts or natural resources and the environment [...] Chapter I. Businesses related to National Safety or Security [...] 2. Domestic transportation by land, water or air, including domestic aviation 
[...] 
List three. Businesses in respect of which Thai nationals are not ready to compete with foreigners  [...] 
(21) Other service businesses, with the exception of service businesses as prescribed in the Ministerial Regulation"((Foreign Business Act, B.E. 2542 (1999))
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"By virtue of the provisions of section 46 paragraph one of the Foreign Business Act, B.E. 2542 (1999) and List Three annexed to the Foreign Business Act, B.E. 2542 (1999), which is the law containing certain provisions in relation to the restriction of rights and liberties of persons, in respect of which section 29 in conjunction with section 33 and section 43 of the Constitution of the Kingdom of Thailand so permits by virtue of provisions of law, the Minister of Commerce issues this Ministerial Regulation, as follows. The following service businesses are the service businesses excluded from (21) of List Three annexed to the Foreign Business Act, B.E. 2542 (1999):
(1) Securities business and other businesses under the law on securities and securities exchange:
 (a) securities trading; (b) serving as an investment consultant; (c) securities underwriting; (d) borrowing and lending securities; (e) mutual fund management; (f) private fund management; (g) venture capital management; (h) granting loans for securities business; (i) serving as a financial consultant; (j) serving as a securities registrar;
 (k) trusteeship of assets of securities companies’ or derivatives traders’ customers; (l) serving as a private fund custodian; (m) serving as a mutual fund supervisor; and
 (n) serving as a debentureholders’ representative;
(2) Derivatives business under the law on derivatives:
 (a) serving as a derivatives dealer; (b) serving as a derivatives advisor; and (c) serving as a derivatives fund manager; and
(3) Serving as a trustee under the law on trust for transactions in capital market.
(4) financial institution business, businesses incidental to or necessary for the operation of a financial institution business and the businesses of companies in the financial group of a financial institution pursuant to the law on financial institutions [amended by Ministerial Regulation Prescribing Service Businesses Which Do Not Require a Foreign Business License (No. 3) B.E. 2560 (2017)]:
 (a) commercial banking business;  (b) bank representative office service business;  (c) Shariah financial service; (d) financial institution agent; (e) cash deposit services under terms of withdrawal on demand by a customer and custodian services; (f) private sector repurchase; (g) agent to receive applications and collect insurance premiums or service fees for export insurance and credit insurance for customers; (h) services relating to financial businesses offered to financial institutions, companies within the financial group, the Bank of Thailand and government agencies; (i) leasing of immovable property; (j) purchase or assignment of loan debts; (k) financing service; (l) documentation relating to customer’s businesses; (m) debt collection or application receiving agent;  (n) hire purchase and leasing.
(5) life insurance business under the law on life insurance; [as amended by Ministerial Regulation Prescribing Service Businesses which Do Not Require a Foreign Business License (No. 2) B.E. 2559 (2016)]
(6) insurance business under the law on insurance.”[as amended by Ministerial Regulation Prescribing Service Businesses which Do Not Require a Foreign Business License (No. 2) B.E. 2559 (2016)]
(7) asset management business under the law on asset management company; [amended by Ministerial Regulation Prescribing Service Businesses Which Do Not Require a Foreign Business License (No. 3) B.E. 2560 (2017)]
(8) representative office of foreign juristic person in international trade service pursuant to the Rules of the Prime Minister’s Office on Establishment of Visa and Work Permit Service Center B.E. 2540 (1997);[amended by Ministerial Regulation Prescribing Service Businesses Which Do Not Require a Foreign Business License (No. 3) B.E. 2560 (2017)]
(9) regional office of foreign juristic person in international trade service pursuant to the Rules of the Prime Minister’s Office on Establishment of Visa and Work Permit Service Center B.E. 2540 (1997);[amended by Ministerial Regulation Prescribing Service Businesses Which Do Not Require a Foreign Business License (No. 3) B.E. 2560 (2017)]
(10) service business to which a government agency under the law on budgetary procedures is a party;[amended by Ministerial Regulation Prescribing Service Businesses Which Do Not Require a Foreign Business License (No. 3) B.E. 2560 (2017)]
(11) service business to which a state enterprise under the law on budgetary procedures is a party[amended by Ministerial Regulation Prescribing Service Businesses Which Do Not Require a Foreign Business License (No. 3) B.E. 2560 (2017)]. "(MINISTERIAL REGULATION PRESCRIBING SERVICE BUSINESSES NOT SUBJECT TO APPLICATION FOR FOREIGN BUSINESS PERMISSION, B.E. 2556 (2013); amended by Ministerial Regulation Prescribing Service Businesses Which Do Not Require a Foreign Business License (No. 3) B.E. 2560 (2017), Ministerial Regulation Prescribing Service Businesses Which Do Not Require a Foreign Business License (No. 2) B.E. 2559 (2016))
Foreign Business Act, B.E. 2542 (1999).
[<a href="https://investmentpolicy.unctad.org/investment-laws/laws/40/thailand-foreign-business-act">Act</a>]