10. Is there a ban on donations from corporations with government contracts to candidates?

ELECTIONS LAW – LAW N. 9,504 OF SEPTEMBER 30th, 1997.

Article 24. Political parties and candidates are prohibited to receive, either directly or indirectly, cash donations or estimated cash amounts, including by means of publicity of any kind, that originate from:
I – foreign entity or government;
II – body under direct or indirect Public Administration or foundation maintained with government resources;
III – concessionaire or permittee authorized to work as a public-utility company;

(...)

IV – legal entity governed by private law which benefits from mandatory contribution set forth in statutory provisions;
V – public utility type of entity;
VI – professional association or union; (...)

VII – not-for-profit legal entity that receives funds from abroad;
VIII – entities devoted to charity and religious affairs;  Item VIII as amended by Article 1 of Law n. 11,300/2006.
IX – sports organizations;  Item IX as amended by Article 3 of Law n. 12,034/2009.
X – non-governmental organizations that receive public funds;
XI – civil society organizations of public interest.  Items X and XI as amended by Article 1 of Law n. 11,300/2006.
Sole paragraph. The prohibitions referred to in this article do no apply to cooperatives whose members are neither concessionaires nor permittees of public
utility, provided they do not receive public funds, pursuant to provisions established in Article 81.  Sole paragraph as amended by Article 3 of Law n. 12,034/2009.