U.S. Medicare Health Insurance: Parts A, B, and D
Author: Disabled World (DW)
Updated/Revised Date: 4 Aug 2026
Table of Contents:
Synopsis - Definition - About This Section - FAQs - Publications - Subtopics
Synopsis
A guide to U.S. Medicare, the health insurance program for people age sixty-five and older and those with certain disabilities, covering Parts A, B, and D coverage.
At a Glance
- 1 - Inpatient psychiatric care is covered for up to 190 days across a beneficiary's lifetime.
- 2 - Part A hospital insurance carries a $912 deductible for an inpatient stay of one to sixty days per spell of illness.
- 3 - Part B has an annual $110 deductible, and most services then require coinsurance of twenty percent of the Medicare-approved amount.
- 4 - Part D prescription drug coverage began on January 1, 2006, and joining late after first eligibility can trigger a lasting penalty.
Topic Definition
- Medicare (United States)
Medicare is the U.S. federal health insurance program established in 1965 under Title XVIII of the Social Security Act to serve people age sixty-five and older, younger people with certain disabilities, and individuals of any age with End-Stage Renal Disease. Administered in connection with the Social Security Administration, it is built around three parts that address different needs: Part A provides hospital insurance covering inpatient care, skilled nursing, hospice, and some home health services; Part B offers medical insurance for physician visits, outpatient care, and medically necessary supplies; and Part D delivers prescription drug coverage through private plans. Most beneficiaries pay no premium for Part A because they or a spouse contributed through payroll taxes while working, while Part B and Part D generally involve monthly premiums, deductibles, and coinsurance.
Overview
U.S. Medicare was established in 1965, authorized under Title XVIII of the U.S. Social Security Act, and is available to people who fall into three categories. Most people become eligible for Medicare by virtue of attaining age sixty-five.
U.S. Medicare is a health insurance program for persons age sixty-five or older, persons under the age of sixty-five years with certain disabilities, as well as people of any age with End-Stage Renal Disease. U.S. Medicare has three kinds of insurance within the program:
- Part A involves Hospital Insurance.
- Part B involves Medical Insurance.
- Part D provides a level of Prescription Drug Coverage.
Medicare is associated with the U.S. Social Security Administration.
Part A Hospital Insurance
The majority of people do not pay a premium for Part A Hospital Insurance because either the person themselves or a spouse has already paid for the coverage through their payroll taxes while working. Medicare Part A Insurance assists in covering inpatient hospital care, to include critical access hospitals, and skilled nursing facilities; although it does not cover either custodial or long-term care. Medicare Part A Insurance assists in covering hospice care, as well as some home health care. Persons with Medicare Part A Insurance must meet specific conditions to receive these benefits.
Part A covers:
- Inpatient hospital services, up to 90 days per "spell of illness"
- Skilled nursing facility services for up to 100 days per spell of illness following a 3+ day hospital stay
- Home health care, up to 100 visits per spell of illness following a 3+ day hospital stay
- Hospice care
- Inpatient psychiatric care, for up to 190 days during a beneficiary's lifetime
- Blood (after the beneficiary pays for the first 3 pints (1.42 liters) per year)
For each "spell of illness," beneficiaries have a $912 deductible for an inpatient hospital stay of 1-60 days and daily coinsurance starting the 61st day. If they use a skilled nursing facility for more than 20 days in a spell of illness, they must pay $114 per day for days.
Part B Medical Insurance:
The majority of people do pay a monthly premium for Part B Medical Insurance. Medicare Part B Insurance assists with coverage of doctors' services, outpatient care, as well as some additional medical services that Medicare Part A Insurance does not cover; for example, some services of physical and occupational therapists, or some home health care services. Medicare Part B assists in paying for covered services and supplies when they are deemed medically necessary.
Part B covers:
- Physicians' services, including office visits and a one-time physical examination for new beneficiaries
- Durable medical equipment (e.g., wheelchairs, oxygen) and supplies
- Outpatient hospital services
- Outpatient mental health services
- Clinical laboratory (e.g., blood tests, some screening tests, etc.) and diagnostic tests
- Outpatient occupational, physical, and speech therapy
- Home health care not preceded by a hospital stay and visits over the 100-day Part A limit
- Some preventive services (e.g., mammograms, diabetes screening)
- Blood (after the beneficiary pays for the first 3 pints (1.42 liters) per year)
Beneficiaries have an annual deductible of $110. In addition, most Part B services require coinsurance of 20 percent of the Medicare-approved amount.
Medicare Part D Prescription Drug Coverage
The majority of people will pay a monthly premium for Medicare Part D Coverage. Beginning on January 1, 2006, Medicare Part D Coverage became available to everyone with Medicare coverage to assist with prescription drug costs. Private companies provide the insurance; beneficiaries can choose among drug plans and pay a monthly premium. As with other forms of insurance, if a person decides not to enroll in a plan when they are first eligible, they may pay a penalty should they decide to join at a later time.
Frequently Asked Questions
When can you first enroll in Medicare
Most people become eligible around their sixty-fifth birthday and can sign up during a seven month initial enrollment period that begins three months before the month they turn sixty-five.
What is the difference between Medicare and Medicaid
Medicare is a federal insurance program based mainly on age or disability, while Medicaid is a joint federal and state program that provides coverage based on income and financial need.
Does Medicare cover dental, vision, and hearing care
Original Medicare generally does not cover routine dental, vision, or hearing services, so beneficiaries who want that coverage often turn to Medicare Advantage plans or separate supplemental insurance.
What is Medicare Part C or Medicare Advantage
Medicare Advantage, sometimes called Part C, is an alternative offered by private insurers that bundles Part A and Part B benefits and often adds extras such as prescription drug coverage.
What is Medigap supplemental insurance
Medigap is private supplemental insurance that helps pay some of the out of pocket costs left by Original Medicare, such as deductibles and coinsurance amounts.
Do you have to pay a penalty for enrolling in Medicare late
Late enrollment can lead to lasting premium penalties for Part B and Part D unless you qualify for a special enrollment period, for example through employer based coverage.
Can you keep Medicare if you travel or move within the United States
Original Medicare coverage stays with you anywhere in the country, though those enrolled in network based plans should check how a move or travel affects their access to providers.
Curated and edited by Ian C. Langtree, Founder & Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team.
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