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. Fund of Mutual Financial Aid of the credit union can be extended by sponsorship contributions from businesses, organizations, including on a returnable basis. Credit unions are financial institutions, financial cooperatives of citizens, and in this capacity they are above all associations of people, not unification of capitals, which is typical, for example, for public companies. 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.