Medicare is a health insurance program for people age 65 and older, people under 65 with certain disabilities, and people of all ages with End-Stage Renal Disease (ESRD). Medicare consists of four programs: Hospital Insurance (Part A), Supplementary Medical Insurance (Part B), Medicare Advantage (Part C), and Medicare Prescription Drug Benefit (Part D). This guide focuses on the Original Medicare program (Parts A and B), also known as Medicare fee-for service.

Medicare is a defined benefit program, and only covers certain devices, supplies, drugs, and biologicals that have been determined to fall within a specific benefit category, are not excluded from Medicare coverage by law, and, in most cases, are reasonable and necessary as described in section 1862(a)(1)(A) of the Act. Medicare’s statutorily-defined benefit categories are defined in Section 1861 of the Act.