If the services the employee is performing are covered under a Federal-State Agreement, then coverage is straightforward—the employee must be covered for FICA. Prior to July 2, 1991, the only way a local government (city, village, county, etc.) could cover its employees under Social Security was for the state to include it under the state’s Federal-State Agreement (Section 218 Agreement) with the Social Security Administration (SSA). The agreement extended Social Security coverage to government employers at the state’s request.
Employees performing services covered by a Federal-State Agreement are required to pay FICA. Social Security coverage obtained through a Federal-State Agreement cannot be terminated. The employee may also be covered by a retirement plan but this must be in addition to the FICA coverage.