Evolution of Medicaid coverage of Medicare cost sharing.

State Medicaid agencies are required to assist low-income Medicare beneficiaries to pay Medicare cost sharing, defined as premiums, deductibles, and coinsurance, as follows: all cost sharing for those below the Federal poverty level (FPL) and otherwise qualifying; Part B premiums for persons with incomes 100-120 percent of FPL; all or a portion Part B premiums for persons 120-175 percent of FPL, limited by funding availability; Part A premiums for persons with disabilities who have worked their way off Social Security and whose incomes are below 200 percent of FPL. States also have the option to extend additional protections or to cover additional Medicare beneficiaries beyond what is mandated by Federal law. Obviously, Federal changes in Medicare may have profound, if not always anticipated, implications for Medicaid. Understanding how current policy on dually eligible beneficiaries came into being may help shape what it will become.