Specialization of credit unions to provide financial services to its shareholders requires a particularly strict regulation of membership and acceptable activities. 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. 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.