Corporate credit unions are united on a cooperative basis in the Central Credit Union (US Central Credit Union). 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. Credit unions are competitors of savings institutions, adding interest on deposits of members. This applies to the shares, as well as to additional funds transferred to the account in the credit union. Unlike banks, in order to use the services of a credit union, you have to become its member, having written an application and having paid thus shares and membership fee.