As of 2015, the best federal agencies to answer Medicare questions are the Social Security Administration and the Centers for Medicare & Medicaid Services. Typically, users contact the SSA first to determine Medicare eligibility and later contact the Centers for Medicare & Medicaid Services to make more specific selections.
The SSA helps users by discussing Medicare eligibility and enrolling in Medicare Part A or Part B. The SSA also processes address changes and requests for new Medicare cards. The Centers for Medicare & Medicaid Services help users enroll in Medicare Part C and D. They also find approved physicians and equipment while answering questions about the quality of hospitals and other healthcare agencies.