Medicaid provides health coverage to 7.2 million low-income seniors who are also enrolled in Medicare. Medicaid also provides coverage to 4.8 million people with disabilities who are enrolled in Medicare. In total, 12 million people are "dually eligible" and enrolled in both Medicaid and Medicare, composing more than 15% of all Medicaid enrollees. Individuals who are enrolled in both Medicaid and Medicare, by federal statute, can be covered for both optional and mandatory categories.

What Medicaid Covers for Medicare Enrollees
Medicare has four basic forms of coverage:

• Part A: Pays for hospitalization costs

• Part B: Pays for physician services, lab and x-ray services, durable medical equipment, and outpatient and other services

• Part C: Medicare Advantage Plan (like an HMO or PPO) offered by private companies approved by Medicare

• Part D: Assists with the cost of prescription drugs
   

Medicare enrollees who have limited income and resources may get help paying for their premiums and out-of-pocket medical expenses from Medicaid (e.g. MSPs, QMBs, SLBs, and QIs).

Full Medicaid Benfits also covers additional services beyond those provided under Medicare, including nursing facility care beyond the 100-day limit or skilled nursing facility care that Medicare covers, prescription drugs, eyeglasses, and hearing aids.
Services covered by both programs are first paid by Medicare with Medicaid filling in the difference up to the state's payment limit.