Upon the enactment of Brazilian Law 9876/99, of November 26, 1999, a part of the system of social contribution payable by companies was modified, and one of the contributions payable by companies was fixed at 15% of the invoice for services rendered by work cooperatives. However, it seems that the requirement for the engaging companies to pay a 15% contribution on the invoices for services from work cooperatives is totally unconstitutional. This article explains the unconstitutionality of this law and discusses the impact of recent court decisions pertaining to this issue.