If you're under 65 and have been approved for Social Security disability benefits, you automatically get Part A and Part B after you receive disability benefits from Social Security or certain disability benefits from the RRB (Railroad Retirement Board) for 24 months. Social Security starts counting the 24 months from the month you were entitled to receive disability, not the month when you received your first check.

NOTE: Residents of Puerto Rico or foreign countries will not receive Part B automatically. They must elect this benefit by contacting Social Security at 1-800-772-1213; TTY users should call 1-800-325-0778.

People with permanent Kidney failure (ESRD - End Stage Renal Disease) or ALS (Amyotrophic Lateral Sclerosis) also called Lou Gehrig's disease get Medicare Part A and Part B beginning with the month they become entitled to disability benefits.

Medicare has four parts:

• Part A (Hospital Insurance). Part A helps cover the cost of inpatient care in hospitals (such as critical access hospitals, inpatient rehabilitation facilities, and long-term care hospitals), inpatient care in a skilled nursing facility (not custodial or long-term care), hospice care services, home health care services, and inpatient care in a Religious Nonmedical Health Care Institution. (Medicare will only cover the non-medical, non-religious health care items and services (like room and board) in this type of facility for people who qualify for hospital or skilled nursing facility care but for whom medical care isn't in agreement with their religious beliefs.) You usually don't pay a monthly premium for Part A coverage if you or your spouse paid Medicare taxes while working.

• Part B (Medical insurance). Part B helps cover the costs of medically-necessary services like doctors' services, outpatient care, home health services, and other medical services. Part B also covers some preventive services. There is a monthly premium that you must pay for Medicare Part B and you have the option to refuse this coverage.

• Part C (Medicare Advantge Plans). Part C plans are administered by private companies contracted with and approved by Medicare. If you join a Medicare Advantage Plan, the plan will provide all of your Part A (Hospital Insurance) and Part B (Medical Insurance) coverage. In all types of Medicare Advantage Plans, you're always covered for emergency and urgent care. Medicare Advantage Plans must cover all of the services that Original Medicare covers except hospice care. Hospice care is always covered by Original Medicare regardless of which Medicare health plan you have. Medicare Advantage plans may offer extra coverage, such as vision, hearing, dental, and/or health and wellness programs. Most include Medicare prescription drug coverage (Part D). In addition to your Part B premium, you usually pay one monthly premium for the services included.

• Part D (Prescription Drug Plans - PDP). Part D helps cover the cost of prescription drugs. If you have Original Medicare or if your Medicare Advantage plan does not include prescription drugs, you may join a stand-alone Prescripton Drug Plan (PDP). Anyone who has Medicare Part A, Part B, or Part C is eligible to enroll in a Part D Prescription Drug Plan. Joining a Medicare prescription drug plan is voluntary, and you pay an additional monthly premium for the coverage.