Medicare Encyclopedia

The yearly period from October 15 to December 7 when anyone with Medicare can make changes to their coverage. During AEP, you can switch between Original Medicare and Medicare Advantage, change Part D plans, or add/drop Medigap policies.

Assignment means a doctor agrees to accept the Medicare-approved amount as full payment. Non-assignment means the doctor doesn't accept Medicare's approved amount and may charge you more through balance billing or excess charges.

When a healthcare provider who doesn't accept assignment bills you for the difference between their charge and what Medicare approves. Federal law limits balance billing to 15% above Medicare's approved amount.

The way Original Medicare measures your use of hospital and skilled nursing facility services. A benefit period begins when you're admitted to a hospital and ends when you haven't received inpatient care for 60 consecutive days.

The final stage of Medicare Part D coverage that begins after you've spent $8,000 out-of-pocket on covered drugs in 2026. Once you reach catastrophic coverage, you pay very little for your medications for the rest of the year.

The federal agency within the Department of Health and Human Services that administers Medicare, Medicaid, and the Children's Health Insurance Program. CMS sets Medicare policy, oversees private insurance companies offering Medicare plans, and manages quality standards.

Your share of costs for a covered healthcare service, calculated as a percentage (like 20%) of the approved amount. Unlike a copayment, which is a fixed dollar amount, coinsurance varies based on the service cost.

A fixed amount you pay for a covered healthcare service, usually when you receive the service. The amount can vary by the type of service.

Prescription drug coverage from an employer, union, or other source that's at least as good as Medicare's Part D coverage. If you have creditable coverage, you can delay enrolling in Part D without facing late enrollment penalties.

The amount you must pay for covered healthcare services before your insurance plan begins to pay. Different parts of Medicare have different deductibles.

A temporary limit on what Medicare Part D prescription drug plans will cover. In 2026, after you and your plan have spent $5,030 on covered drugs, you enter the coverage gap where you pay 25% of costs until reaching catastrophic coverage.

Medical equipment ordered by your doctor for use at home that can withstand repeated use and is used for a medical purpose. Medicare Part B covers 80% of the cost after you meet your deductible.

Additional amounts that doctors who don't accept assignment can charge above Medicare's approved amount. Federal law limits excess charges to 15% above the Medicare-approved amount. Medigap Plans F and G cover excess charges.

A Medicare program that helps people with limited income and resources pay for Part D prescription drug costs. Extra Help pays for monthly premiums, annual deductibles, and copays, with no coverage gap or late penalties.

The list of prescription drugs covered by a Medicare Part D plan or Medicare Advantage plan with drug coverage. Formularies are organized into tiers with different cost-sharing amounts, and they can change during the year.

An annual enrollment period from January 1 to March 31 when you can sign up for Medicare Part A and/or Part B if you didn't enroll during your Initial Enrollment Period. Coverage starts July 1, and you may owe a late enrollment penalty.

A type of Medicare Advantage plan that typically requires you to get your care from doctors and hospitals in the plan's network (except emergency care). You usually need referrals from your primary care doctor to see specialists.

Part-time or intermittent skilled nursing care and home health aide services provided in your home when you're homebound and under a doctor's care. Medicare Part A and Part B cover home health services at 100% with no copay or deductible if you meet the requirements.

Special care for people who are terminally ill, focusing on comfort rather than cure. Medicare Part A covers hospice care when a doctor certifies you're terminally ill (life expectancy of 6 months or less). There's no deductible or copay for most services.

Your first chance to sign up for Medicare. The IEP is a 7-month period that includes the 3 months before your 65th birthday month, your birthday month, and the 3 months after. Missing this deadline can result in permanent late penalties.

An extra charge added to your Medicare Part B and Part D premiums if your income is above a certain level. IRMAA is based on your income from two years ago (reported on your tax return).

A permanent 10% increase in your Part B premium for each 12-month period you were eligible but didn't enroll, unless you had creditable coverage. You pay this penalty for as long as you have Part B.

A permanent increase in your Part D premium if you go 63 or more consecutive days without creditable prescription drug coverage after your Initial Enrollment Period ends. The penalty is calculated as 1% of the national base beneficiary premium for each month you were late.

Medicare Part A provides 60 lifetime reserve days for hospital stays longer than 90 days in a benefit period. Once you use these 60 days, they're gone—you can't get them back. You pay a daily coinsurance ($844 in 2026).

A special period from January 1 to March 31 when people already enrolled in a Medicare Advantage plan can switch to a different Medicare Advantage plan or return to Original Medicare (and join a Part D plan). You can only make one change during MA-OEP.

An alternative way to get Medicare coverage through private insurance companies approved by Medicare. These plans include all Part A and Part B services, and usually include Part D prescription drug coverage plus extra benefits like dental and vision.

State-run programs that help pay Medicare premiums, and sometimes deductibles and coinsurance, for people with limited income and resources. The four programs are QMB, SLMB, QI, and QDWI, with different income limits and benefits.

Supplemental insurance sold by private companies to help pay for costs that Original Medicare doesn't cover, like coinsurance, copayments, and deductibles. Medigap plans are standardized and labeled with letters (Plan G, Plan N, etc.).

The doctors, hospitals, and other healthcare providers contracted with a Medicare Advantage or Part D plan. Using in-network providers typically costs less than using out-of-network providers. Original Medicare has no network—you can see any provider that accepts Medicare.

The most you'll have to pay for covered services in a year. Once you reach this limit, your plan pays 100% of covered services for the rest of the year. Original Medicare does not have an out-of-pocket maximum, but Medicare Advantage plans do.

Hospital insurance that helps cover inpatient care in hospitals, skilled nursing facility care, hospice care, and some home health care. Most people don't pay a premium for Part A if they or their spouse paid Medicare taxes while working.

Medical insurance that helps cover doctor services, outpatient care, medical supplies, and preventive services. Part B requires a monthly premium, which in 2026 is $202.90 for most people.

Part C (Medicare Advantage) is an alternative to Original Medicare that bundles hospital and medical coverage, usually with drug coverage included. Part D is standalone prescription drug coverage you add to Original Medicare or a Medicare Advantage plan without drugs.

Prescription drug coverage offered through private insurance companies approved by Medicare. You can add Part D to Original Medicare or get it included in a Medicare Advantage plan.

One of the most popular Medigap supplement plans. Plan G covers nearly all out-of-pocket costs except the Part B deductible. It's standardized, meaning Plan G from any insurance company offers the same benefits.

A Medigap supplement plan that offers good coverage at a lower premium than Plan G. Plan N requires small copays for doctor visits ($20) and emergency room visits ($50), and you pay Part B excess charges.

A type of Medicare Advantage plan that allows you to use both in-network and out-of-network providers without referrals. You pay less when using in-network providers but have flexibility to see specialists directly and go out-of-network for higher costs.

The amount you pay (usually monthly) for your health insurance or prescription drug coverage. You pay premiums even if you don't use any medical services during that time.

Healthcare services that help prevent illness or detect health problems early. Medicare Part B covers many preventive services at 100% with no coinsurance or deductible, including annual wellness visits, flu shots, mammograms, and various screenings.

Approval from your Medicare plan before receiving certain services or medications. Prior authorization ensures the service is medically necessary and covered by your plan. Some Medicare Advantage and Part D plans require this for expensive drugs or procedures.

A time outside the regular enrollment periods when you can sign up for Medicare or make changes to your coverage due to certain life events, such as moving, losing other coverage, or qualifying for Extra Help.

A facility that provides skilled nursing care and rehabilitation services. Medicare Part A covers up to 100 days per benefit period in an SNF after a qualifying 3-day hospital stay. Days 1-20 are covered at 100%, days 21-100 require coinsurance ($211.50/day in 2026).

The federal agency that administers Social Security benefits and handles Medicare enrollment. You apply for Medicare through the SSA, and they process IRMAA determinations and appeals. Many people are auto-enrolled in Medicare when they start receiving Social Security benefits.

A quality measurement system that rates Medicare Advantage and Part D plans on a scale of 1 to 5 stars. Ratings are based on factors like customer service, care quality, member complaints, and drug safety. Plans with 5 stars are considered excellent.

Healthcare services provided remotely through video calls, phone calls, or online portals. Medicare covers certain telehealth services, especially for behavioral health. Medicare Advantage plans often offer broader telehealth benefits than Original Medicare.