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

Article 19, Decree-law of 2011-87, 2011, of the  organization of political parties: chapter 19 - Political parties are prohibited from accepting:
- Direct or indirect financing, in cash or kind, issued by any foreign entity.
- Direct or indirect financing from an unknown source.
- Aid, donations, and gifts issued by legal entities, whether private or public, with the exception of funding included in the state budget.
- Donations, gifts, and bequests issued by natural persons whose annual value exceeds sixty thousand (60,000) dinars for each donor.

Article 75 (new), organic-law 2014-16, 26th May, of the elections and referendum - Amended under Decree No. 55 of 2022 dated September 15, 2022:
the electoral campaign and the referendum campaign shall be financed exclusively through self-financing and private financing in accordance with what is regulated by this law.

Unofficial English translation.

Political parties are prohibited from accepting help, gifts, and donations from people and public or private legal entities.