12. Is there a ban on donations from corporations with partial government ownership to candidates?

Section 9. (1) A list of candidates may be submitted by:
1) a political party registered in accordance with the procedures laid down in law which has been
established not later than one year before the election of the Saeima and which has at least 500 members;
2) an alliance of political parties registered in accordance with the procedures laid down in law if all
political parties belonging to the alliance of political parties have been established not later than one year
before the election of the Saeima and if the alliance of political parties has at least 500 members.

Law on the Election of the Saeima, Article 9 (1) (2).

No donations to individual candidates allowed; no individual candidates stand for elections, only party lists. 
Therefore, all donations have to be directly transferred to a political party, no donations to individual candidates on the party lists are allowed. Additionally, no legal entities can donate to political parties.