Foreign ownership of land is limited to 49%. According to legal practitioners: "Generally, foreign individuals or corporations are not permitted to hold title to land, but they are allowed to obtain leasehold interests. However, under existing regulations, foreigners may purchase a freehold interest in land if they are: Joint ventures where foreign parties control not more than 49% of the company; Foreign manufacturers promoted by the BOI; Oil concessionaires under the Petroleum Act; Businesses located in certain industrial estates [...] (Jones Lang Lassalle, 2018)" 
In the OECD FDIRRI, it is assumed that foreign ownership of land is limited to 49%; ownership in excess of this amount is only permitted for business purposes and in restricted situations which are not taken into account under real estate investments.
"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.
[...]
Annex - List one. Businesses stricto sensu not permissible to foreigners by special reason:
[...] (9) Land trading [...]"((Foreign Business Act, B.E. 2542 (1999))
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"[...] CHAPTER VIII - Determination of Aliens’ Right to Land
Section 86. An alien may acquire land only by virtue of the provisions of a treaty that provides for ownership of immovable property and also subject to the provisions
of this Code.[...]
Section 87. The amount of land permitted under the preceding Section shall be as follows:
(1) for residence, not more than 1 rai per family;
(2) for commercial purposes, not more than 1 rai;
(3) for industrial purposes, not more than 10 rai;
(4) for agricultural purposes, not more than 10 rai per family;
(5) for religious purposes, not more than 1 rai;
(6) for public charity purposes, not more than 5 rai;
(7) for cemeterial purposes, not more than 1/2 rai per family.
If any alien wishes to have right to land for industrial purposes in excess of that provided in (3), and if deemed appropriate, the Council of Ministers may permit acquisition of land in excess of the limit prescribed, by imposing conditions thereon, and the provisions of Section 48 shall apply mutatis mutandis.
[...]
CHAPTER IX - DETERMINATION OF RIGHT TO LAND OF CERTAIN TYPES OF JURISTIC PERSONS
Section 97. The following juristic persons shall have right to land as if they were an alien:
(1) A limited company or public limited company whose shares constituting its registered capital are held by aliens by more than forty-nine per cent of its registered capital, or whose alien shareholders are more than one-half of the total number of its shareholders, as the case may be [as amended by the Land Code Amendment Act (No. 6) B.E. 2535 (1992)];
For the purposes of this Chapter, if any limited company issues bearer share certificates, such a share certificate shall be deemed to be held by an alien.
(2) A limited partnership or registered ordinary partnership whose contributions by aliens are more than forty-nine per cent of its total capital or whose alien partners are more than one-half of the total number of its partners, as the case may be [as amended by the Land Code Amendment Act (No. 6) B.E. 2535 (1992)];
(3) An association including co-operative whose alien members are more than one-half of its total number of members or which operates exclusively or substantially for the benefit of aliens;
(4) A foundation whose objectives are exclusively or substantially for the benefit of aliens.
[...]
Section 99. If a juristic person under Section 97 or Section 98 is to acquire or to dispose of right to land, the provisions of Chapter 8 shall apply mutatis mutandis, and such juristic person shall have the same duties and liabilities as those provided for aliens and persons in general [as amended by the Land Code Amendment Act (No. 12) B.E. 2551 (2008)].
Section 100. For any juristic person which acquired land while it did not come under the provisions of Section 97 and Section 98, if subsequently it comes under the provisions of Section 97 or Section 98, the provisions of Section 95 shall apply mutatis mutandis.[...]"(ACT PROMULGATING THE LAND CODE B.E. 2497 (1954))
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"Section 19. An alien person or a juristic person deemed alien by law may have an ownership in a unit if it satisfies the following conditions [as amended by the Condominium Act (No. 2), B.E. 2534 (1991)]:
(1) the person obtains a residence permit in accordance with immigration law;
(2) the person obtains a permit to enter the country in accordance with the law on investment promotion;
(3) the person is a juristic person under section 97 and section 98 of the Land Code, registered as a juristic person under Thai law.
(4) the person is a alien juristic person under the Announcement of the Revolutionary Council No. 281, dated the 24th November B.E. 2515 (1972), and obtains an investment promotion certificate in accordance with the law on investment promotion.
(5) the person is an alien person or a juristic person deemed alien by law, bringing foreign currency into the country, withdrawing fund from a Thai baht account of a person having a place of residence outside of the country, or withdrawing fund from a foreign currency-based deposit account [as amended by the Condominium Act (No. 3), B.E. 2542 (1999)]
Section 19 bis.Ownership of each condominium shall not be held by alien persons or juristic persons under section 19 greater than forty-nine percent of the total area
of every unit in the condominium at the time of registration under section 6 [as amended by the Condominium Act (No. 4), B.E. 2551 (2008)]. [...]" (CONDOMINIUM ACT, B.E. 2522 (1979))
Foreign Business Act, B.E. 2542 (1999)
ACT PROMULGATING THE LAND CODE B.E. 2497 (1954)
CONDOMINIUM ACT, B.E. 2522 (1979),as amended by Condominium Act (No. 2), B.E. 2534 (1991), Condominium Act (No. 3), B.E. 2542 (1999) and Condominium .Act (No. 4), B.E. 2551 (2008)
[<a href="https://investmentpolicy.unctad.org/investment-laws/laws/40/thailand-foreign-business-act">Act</a>],[<a href="http://web.krisdika.go.th/data/outsitedata/outsite21/file/Act_Promulgating_the_Land_Code_BE_2497_(1954).pdf">Act</a>],[<a href="http://www.krisdika.go.th/wps/wcm/connect/8515ad004ba49805a155a38b0853d392/CONDOMINIUM+ACT%2C+B.E.+2522+%281979%29.pdf?MOD=AJPERES&CACHEID=8515ad004ba49805a155a38b0853d392">Act</a>],[<a href="http://www.joneslanglasallesites.com/investmentguide/country/thailand/restrictionsonforeignpropertyownership">Other</a>]