4. Is there a ban on corporate donations to candidates?

Section 74    prohibits political parties or members from accepting donations of money, property, or other benefits from:

(1)Persons who do not have Thai nationality; (2) Foreign legal entities engaged in business or or registered branches in or outside the Kingdom; (3) Juristic persons registered in the Kingdom with non-Thai nationals having more than 49% of their capital or shareholders. In the case of a public limited company registered on the Stock Exchange of Thailand, it shall be considered as it appears in the shareholders’ register of such company. Unidentified shares held or held by representatives of anonymous persons shall be deemed to be shared held by non-Thai national; (4) A group of persons or juristic person funded or subsidized by a foreign country whose purpose is to operate for the benefit of persons who are not Thai nationals or whose managers or directors are non-Thai nationals; (5) A person, group of persons or juristic persons who receive donations for the operation of a political party or to carry out political activities from persons, groups of persons or juristic persons pursuant to (1), (2), (3), or (4); (6) A person, faculty, or entity of the same nature as (1), (2), (3), (4), or (5) as determined by the Board. The provisions of paragraph one do not apply to cases where a member accepts donations of such money, property, or other benefits other than for political activities.

Section 75   A person, group of persons, or juristic persons under Section 74 shall not donate money, property, or other benefits to a political party or its members for the operation of a political party or to carry out political activities.

Section 76  Prohibits any government agency, state enterprise, any other state agency or state-owned entity, from donating money, property or other benefits to a political party or participation in activities under Section 64.

An entity in which a state holds a majority of shares pursuant to paragraph one shall mean any entity in which the State is a partner or holds the largest number of shares among the partners or other shareholders or amounts to one-third of all partnerships or shares of that entity. The provisions of paragraph one shall apply to temples or other legal entities for religious purposes and religious organizations, regardless of whether they have legal entity status or not. The Board of Directors may also apply to other legal entities that are intended for the public interest or entities that are not intended for profits.

Organic Act on Political Parties. 2017 (Unofficial translation by researcher)