5. Is there a ban on donations from Trade Unions to political parties?

1. Donations and other free benefits may not be accepted by a party from [...]
d) civic associations, foundations, non-profit organizations providing services of general interest, non-investment funds, interest associations of legal entities, associations of municipalities and organizations with an international element, [...]
Source: § 24(1) ,Law No. 85 on Political Parties and Movements, 2005 (amended 2019)

There is no explicit ban on donations from Trade Unions to political parties. However, there is ban on donation from civic associations, foundations, non-profit organizations providing services of general interest.