Why Does Cash App Need SSn? Social security number verifies the identity of a user in the Cash app or any payment service application and assures that complete verification of a person is done. And once the Cash app ssn verification is complete successfully, they can easily avail various features of the Cash app. SSn verification is required when you transfer money or you do anything which is confidential in the app. Visit our website and access complete knowledge of Cash app ssn and related things.