Corporate credit unions are united on a cooperative basis in the Central Credit Union (US Central Credit Union). Typically, donor contributions to the credit unions are targeted and used in the same statutory requirements and restrictions as the Mutual Financial Aid fund as a whole. Like the credit cooperatives, credit unions form associations of a higher level, which are called corporate credit unions. Income received by the credit union shall be distributed among the shareholders or spent for the depreciation of services, that is, are the most effective means of meeting the needs of shareholders. In the credit union compensation for use of the loan (interest) is a source of compensation for savings. Historically, credit unions have grown from the experience of credit cooperatives, but they took the experience of organizations of mutual aid of citizens by moving methods of social self-protection from labor and toward consumption.