Corporate credit unions are united on a cooperative basis in the Central Credit Union (US Central Credit Union). The difference between credit unions and banks is clearly is apparent when comparing the structure of assets and liabilities of credit unions and banks. Until the 70's there was a proliferation of the U.S. credit unions due to the increase of their number and the number of shareholders, although it must be acknowledged that there was also and a qualitative growth. The relationship between credit unions and shareholders arise from the membership and are not customer relationship. Credit Union - a non-profit financial institution specialized in mutual financial assistance by providing savings and credit services to their members. Credit unions base their activities on savings of shareholders, their shares and savings contributions, which make up the fund of mutual financial assistance - a source of cash loans to shareholders.