Membership in the credit union is voluntary and is open to all citizens bound by with joint work or residence, who wished to create a credit union to use its services and are willing to take on relevant commitments and responsibilities. Historically, credit unions were preceded by widespread development of credit cooperation in many countries of Europe and America. Typically new members of the credit union become citizens having suretyship or recommendations from their friends - members of the credit union. The relationship of shareholders with credit union are not client-based, they are co-operative, based on different principles and standards, in particular, on the principles of the law of obligations. Shareholders in corporate organizations are basic credit unions, besides the same union can be a shareholder of several corporate organizations. The right to use the services of the credit union have only its members. Credit cooperatives and credit unions exist in many different forms. The main differences relate to the nature of the membership and the opening of a credit institution. Credit unions historically formed as a special form of social support, initially taken upon themselves the social mission of protecting the interests of citizens in the field of financial services. Unlike banks credit unions limit their activities to a closed circle of people.