The federal government designed Medicare to provide affordable healthcare to people in the United States, including people ages 65 years or older as well as younger people with certain health conditions.
According to the Centers for Medicare and Medicaid Services (CMS), in September 2024, there were more than 68 million enrollees in the Medicare program.
Medicare has various parts and options for healthcare coverage. Original Medicare combines Part A (hospital insurance) and Part B (medical insurance). After an individual pays the deductible, Medicare pays a share of healthcare costs.
This article looks at the details of Original Medicare, including eligibility, enrollment options, and costs.
Glossary of Medicare terms
- Out-of-pocket cost: This is the amount a person must pay for care when Medicare does not pay the total amount or offer coverage. Costs can include deductibles, coinsurance, copayments, and premiums.
- Premium: This is the amount of money someone pays each month for Medicare coverage.
- Deductible: This is an annual amount a person must spend out of pocket within a certain period before Medicare starts to fund their treatments.
- Coinsurance: This is the percentage of treatment costs that a person must self-fund. For Medicare Part B, coinsurance is 20%.
- Copayment: This is a fixed dollar amount a person with insurance pays when receiving certain treatments. For Medicare, this usually applies to prescription drugs.
Federally funded Medicare has four main parts covering various healthcare services. In general, the program is for older people in the United States, although younger people with disabilities or some medical conditions may also be eligible for Medicare.
The program consists of:
With Original Medicare, people can visit any doctor, clinic, or hospital countrywide, provided it accepts Medicare payment. The government pays the health provider directly for the service.
The Original Medicare program began in 1965, which includes Part A and Part B.
A person enrolled in the program can generally use any doctor, clinic, hospital, or other healthcare professional enrolled in Medicare and accepting new Medicare patients. They also don’t have to choose a primary doctor and may not need a referral to see a specialist.
In general, prescription drug coverage is not included in Original Medicare, although a person may enroll in a Medicare Part D plan. Some Part C (Advantage) plans also offer prescription drug coverage.
A person may also want to consider a Medicare Supplement Insurance policy, known as Medigap, for any out-of-pocket costs.
Medicare Part A covers inpatient stays in a hospital or skilled nursing facility, and home care and hospice services.
Hospital or skilled nursing facility
If a person enrolled in Original Medicare is in the hospital, Part A covers:
- a semiprivate room
- general nursing care
- meals
- some drugs and medical supplies
- rehabilitation services, such as physical therapy
- lab and imaging tests
- operating room fees
- specialist unit care, such as intensive care
Hospice
In a hospice, Part A covers general nursing care, including medications, that help people with a terminal illness manage their symptoms and pain.
Home healthcare
For home healthcare, Part A covers:
- rehabilitation services, such as physical therapy
- skilled healthcare if a person cannot leave their home
- some medical supplies that are prescribed by a doctor as part of a person’s care, such as wound dressings
There are a few items or services not covered by Original Medicare Part A, such as:
- private rooms, unless medically necessary
- cosmetic procedures
- private nursing care
- televisions or telephones in the room
- personal care items
- doctors’ fees during an inpatient stay, although Part B covers this
- long-term resident fees for nursing homes or assisted living facilities
- dentures
- the majority of dental care
Medicare Part B covers medically necessary services to diagnose or treat an existing medical condition, including doctor’s visits, chiropractors, and some preventive services. It also covers medically necessary care, such as cataract surgery or surgeries following an injury.
Part B coverage also includes:
- ambulance services for transport to a hospital or skilled nursing facility
- certain chiropractic services for lower back pain
- clinical research services, including drug trials and treatments
- diabetes supplies, such as blood sugar test strips and testing monitors
- emergency room services for illness or injury
- durable medical equipment, such as walking equipment, oxygen supplies, and beds
- mental health services, such as visits to a psychiatrist or specialist nurse practitioner
- screenings for bone density, diabetes, glaucoma, and some cancers
Some of the gaps in Medicare Part B coverage include:
- routine vision, hearing, and dental services
- routine foot care, unless for foot problems triggered by health conditions such as diabetes, cancer, or chronic kidney disease
- home safety items, such as grab bars
- long-term care in nursing homes or assisted living facilities
- medically unnecessary services, such as cosmetic surgery
People typically become eligible for Medicare when they reach 65 years of age. Younger individuals may also qualify if they meet specific requirements, including:
- disability, for which a person must receive Social Security Disability Insurance (SSDI)
- illness, such as end stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS)
- family relationship coverage, when an individual’s parent or a spouse paid Medicare taxes for a certain period
This online tool can help a person check if they are eligible for Medicare.
Some individuals are automatically enrolled in Original Medicare, while others may have to wait until they are eligible and sign up manually.
Automatic enrollment
If a person gets SSDI for at least 24 months, they are automatically enrolled in Original Medicare after they receive their 25th SSDI check.
For a person with ALS, Medicare coverage begins automatically during the first month in which the SSDI benefits start.
People who receive retirement benefits from either Social Security or the Railroad Retirement Board are enrolled in Medicare Part A when they are 65 years old.
Manual enrollment
Medicare has set times during the year when eligible individuals can enroll. Enrollment dates include:
- Initial Enrollment Period (IEP): This enrollment period begins 3 months before a person turns 65 years old, includes their birth month, and extends a further 3 months, for a total of 7 months. People enrolling in Original Medicare in the IEP avoid late enrollment penalties.
- General Enrollment Period (GEP): The GEP is from January 1 to March 31 each year, with Original Medicare coverage starting on July 1.
- Open Enrollment Period (OEP): The OEP, also known as the Annual Enrollment Period, runs from October 15 to December 7 each year. During this window, people can enroll in Medicare parts C and D.
- Special Enrollment Period (SEP): Specific events trigger an SEP, such as divorce or moving to a new house. An SEP typically lasts for 8 months.
Medicare provides an online tool for people to review eligibility for the program and when they can enroll.
There are various costs associated with Original Medicare.
Part A costs
Medicare Part A is usually premium-free, provided a person has paid Medicare taxes for 40 quarters or more.
People who receive retirement benefits from Social Security or the Railroad Retirement Board also receive premium-free Part A. If the individual or their spouse had Medicare-covered government employment, they could also receive premium-free Part A.
Part A premium
If a person has to pay a premium for Part A, the cost depends on how many quarters they paid Medicare taxes:
- If they paid taxes for 30 to 39 quarters, the monthly premium is $285 in 2025.
- If they paid taxes for fewer than 30 quarters, the monthly premium is $518 in 2025.
Additional costs
A person must also pay a deductible of $1,676 in 2025 for covered health services, per benefit period.
If a person stays in the hospital, there is no coinsurance for the first 60 days. For days 61 to 90, there is $419 daily coinsurance. This increases to $838 per day from days 91 to 150. After day 150, the person pays 100% of the cost.
Part B
The costs with Part B include premiums and deductibles.
Premiums
An individual’s income determines what they pay for the Part B premium.
For people with an annual income of less than or equal to $106,000, the premium in 2025 is $185.00 per month. However, a person with a yearly income of $500,000 or more will have a monthly premium in 2025 of $628.90.
Other costs
After paying the Part B deductible of $257, a person will pay 20% of any Medicare-approved amount for healthcare.
Original Medicare provides healthcare coverage through Part A (hospital insurance) and Part B (medical insurance). Typically, people over 65 years of age qualify for coverage, although younger people may be eligible if they are living with a disability or medical condition.
People can enroll in Original Medicare during specific periods during the year, including a 7-month period around their 65th birthday.
