Medicare Glossary: Simple Definitions & Terms

The period each year from October 15 through December 7 when Medicare beneficiaries can change their Medicare Advantage or Part D drug plans. Changes take effect January 1 of the following year.

A document that Medicare Advantage and Part D plans must send to enrollees by September 30 each year. It outlines any changes to the plan's costs, coverage, or service area that will take effect January 1.

A prescription drug sold under its trademarked name. Brand-name drugs are typically more expensive than generic alternatives and may be in a higher formulary tier, requiring a higher copay or coinsurance under Part D.

The phase of Medicare Part D drug coverage that begins after you and your plan have spent a certain total amount on covered drugs in a year. In this phase, your copays are significantly reduced. In 2025, out-of-pocket costs are capped at $2,000 annually.

Choosing Medicare coverage becomes easier when you stop looking for a universally better plan and start asking what fits your life. Your doctors, prescriptions, travel habits, and comfort with unexpected bills all matter.

A plan that works well for your neighbor may create difficulties for you. Perhaps you see specialists across different health systems. Perhaps keeping monthly expenses manageable matters most. Neither priority is wrong.

Understanding Medicare Advantage vs Medigap means looking beyond advertisements and comparing how each approach works when you actually need care.

Understand What You Are Comparing

Medicare Advantage and Medigap serve different purposes.

Medicare Advantage is a way to receive your Medicare benefits through a private insurance plan. You remain in Medicare, but the plan administers your covered hospital and medical benefits. Most plans also include prescription drug coverage.

Medigap, also called Medicare Supplement Insurance, works alongside Original Medicare. It helps pay certain expenses left after Medicare pays, depending on the policy.

You cannot use Medigap to pay Medicare Advantage copayments or deductibles. The meaningful comparison is Medicare Advantage versus Original Medicare with Medigap and, when needed, separate drug coverage. Medicare explains this distinction in its Medigap basics.

Compare Your Total Costs

A monthly premium is only part of your healthcare budget.

With Medicare Advantage, review the plan premium alongside copayments, coinsurance, deductibles, and its annual limit for covered medical services. You generally continue paying your Part B premium.

That medical spending limit does not include every expense. Premiums, prescription costs, and services outside the plan’s coverage need separate consideration.

With Medigap, you pay a policy premium in addition to applicable Medicare and drug plan premiums. Depending on the policy, more of your expenses for Medicare covered services may be handled by your supplement.

Ask yourself: would you prefer paying more regularly for greater predictability, or accepting more costs when you receive care?

Compare a routine year with a year involving hospital treatment and ongoing specialist appointments. Medicare’s coverage comparison outlines the financial differences.

Check Access to Your Doctors

Start with the people already involved in your care.

Original Medicare generally lets you visit doctors and hospitals that accept Medicare throughout the country. Most standard Medigap policies follow that access, although Medicare SELECT policies have additional network requirements.

Medicare Advantage plans may require you to use a provider network for routine care. Some allow care outside the network at a different cost.

Ask your doctor’s office about the exact plan you are considering. Accepting Medicare does not necessarily mean participating in a particular Medicare Advantage plan.

Confirm your hospital, specialists, laboratories, and treatment facilities too. A familiar insurance company name is not enough to establish that your care team participates.

Understand Referrals and Approval Requirements

Doctor access and permission for a service are separate questions.

Some Medicare Advantage plans require specialist referrals. Plans may also require prior authorization before covering certain treatments, equipment, or services.

Original Medicare generally has fewer prior authorization requirements, but coverage rules still apply. Having Medigap does not turn a service Medicare excludes into a covered benefit.

If you receive ongoing treatment, ask how the proposed coverage handles it. Discuss therapy, imaging, medical equipment, and specialist procedures before enrolling.

The practical question is not simply whether something is covered. It is what must happen before you can receive covered care.

Review Prescriptions and Additional Benefits

Most Medicare Advantage plans include prescription coverage. Compare your medications against the plan’s covered drug list, and check pharmacy arrangements and restrictions.

Medigap policies sold today do not include prescription drug coverage. People using Original Medicare with Medigap generally consider a separate Part D plan unless they have other suitable drug coverage.

Some Medicare Advantage plans include dental, vision, hearing, or fitness benefits. Review their limits and participating providers before assigning them much value.

Medigap generally does not cover routine dental care, eyeglasses, or hearing aids. Its central purpose is helping with eligible Medicare expenses. See Medicare’s explanation of what Medigap covers.

Consider Where You Spend Your Time

Travel can change which coverage feels practical.

If you regularly stay with family elsewhere in the country, broad access through Original Medicare may be useful. With Medicare Advantage, check how the specific plan handles routine care while you are away.

Emergency coverage is different from access to scheduled appointments outside your usual area.

For international travel, neither approach should be assumed to provide comprehensive protection. Some Medigap policies include limited foreign travel emergency benefits, and some Medicare Advantage plans offer travel benefits. Read the conditions before relying on them.

Think About Switching Before You Enroll

Do not choose coverage assuming you can always move into Medigap later without questions.

Medigap has a protected enrollment opportunity linked to age and Part B enrollment. Outside that window, insurers may use medical underwriting unless another protection applies.

State rules and certain circumstances can provide additional rights. However, permission to leave Medicare Advantage does not automatically guarantee acceptance into Medigap.

Before making a switch, confirm your eligibility, application outcome, prescription arrangements, and effective dates. Medicare’s Medigap buying guidance explains these protections.

Frequently Asked Questions

Is Medicare Advantage always cheaper?

No. Compare premiums with expected treatment costs, prescription expenses, and possible spending during a difficult health year. The answer depends on the specific coverage and your needs.

Does Medigap cover everything?

No. Benefits depend on the policy, and expenses for services Medicare does not cover generally remain your responsibility.

Can I have Medicare Advantage and Medigap together?

Medigap cannot supplement Medicare Advantage. Choose the coverage approach that fits your situation rather than treating them as complementary policies.

Which option is better for frequent specialist visits?

Check the specialists you need, referral rules, treatment approvals, and expected costs. Frequent visits alone do not determine the best choice.

Choose With Your Own Priorities in Mind

The better option supports your care, fits your budget, and leaves you comfortable with its rules.

Prepare your doctor and medication lists, identify your priorities, and find a Medicare agent through Find My Medicare Agent. An independent professional can help you compare available options and understand the tradeoffs before you decide.

A phase in Medicare Part D where you pay a higher share of your drug costs after your total drug spending reaches a certain amount. Sometimes called the "donut hole." In 2025, the coverage gap was effectively eliminated for most beneficiaries due to the Inflation Reduction Act.

The process of leaving a Medicare Advantage or Part D plan. You can only disenroll during specific enrollment periods, such as the Annual Enrollment Period or a Special Enrollment Period. When you disenroll from a Medicare Advantage plan, you return to Original Medicare.

A detailed description of what your Medicare Advantage or Part D plan covers, how much it costs, and how the plan works. Plans must send you an EOC each year by October 15.

A federal program that helps people with limited income and resources pay Part D prescription drug costs, including premiums, deductibles, and copays. Also called the Low Income Subsidy (LIS).

A list of prescription drugs covered by a Medicare Part D plan or Medicare Advantage plan with drug coverage. Drugs are organized into tiers, with each tier having a different cost. Plans can change their formularies annually.

A prescription drug that has the same active ingredients, dosage, and effectiveness as a brand-name drug but is sold at a lower price after the brand-name patent expires. Generic drugs are typically in lower Part D tiers with lower copays.

A set amount of time after a premium due date, typically extending into the following month or two, during which you can still pay a missed Medicare Advantage, Part D, or Medigap premium before losing coverage.

The point at which your total drug spending under Part D reaches a set threshold, after which you enter the coverage gap phase. This limit applies to the combined spending by you and your plan.

An extra amount added to your Part B and Part D premiums if your income is above a certain threshold, based on the tax return from two years earlier. IRMAA is reassessed annually and can be appealed after certain life-changing events like retirement.

A higher premium added permanently to your Part B or Part D premium if you don't sign up for coverage when you are first eligible and don't have other qualifying coverage. The Part B penalty is 10% for each full 12-month period you were eligible but didn't enroll. The Part D penalty is 1% of the national base premium per month.

See Extra Help. A federal program that reduces Part D costs for people with limited income and resources, covering most premiums, deductibles, and copays.

A Medicare Advantage plan that bundles medical coverage (Part A and B) together with prescription drug coverage (Part D) into a single plan.

The formal name for Medicare Advantage. A type of Medicare coverage offered by private insurers that combines Part A, Part B, and usually Part D coverage into one plan.

Medicare prescription drug coverage. A voluntary program offered through private insurers to help pay for outpatient prescription drugs. Plans vary in which drugs they cover (formulary) and what you pay. You may owe a late enrollment penalty if you don't join when first eligible.

For Medicare Advantage, the period from January 1–March 31 each year when enrolled MA beneficiaries can switch to a different MA plan or return to Original Medicare (with Part D if desired). Changes take effect the first of the following month.

The amount you pay for your Medicare coverage, typically deducted monthly. Part A is premium-free for most people. Part B has a standard monthly premium (adjusted for income). Medicare Advantage and Part D plans have their own premiums in addition to Part B.

A stand-alone Medicare Part D plan that provides prescription drug coverage for people enrolled in Original Medicare. PDPs are separate from Medicare Advantage plans that already include drug coverage.

Approval that your Medicare Advantage or Part D plan may require before you receive certain services or medications. Without prior authorization, the plan may not cover the cost. Original Medicare rarely requires prior authorization.

The geographic area where a Medicare Advantage or Part D plan is available and provides coverage. Plans may have different networks and costs in different parts of their service area. Moving outside a plan's service area may trigger a Special Enrollment Period.

The minimum level of coverage that Medicare Part D prescription drug plans must provide. Plans may offer enhanced coverage above this standard, but all must include at least the standard benefit.

A 1–5 star quality rating system that CMS uses to measure how well Medicare Advantage and Part D plans perform. Ratings are based on measures including member experience, customer service, and managing chronic conditions. Higher-rated plans may receive bonus payments.

A coverage requirement where you must try a less expensive drug first before your plan will cover a more expensive one. Commonly used in Medicare Advantage and Part D plans to control costs.

A standardized document that Medicare Advantage and Part D plans must provide that summarizes the plan's costs, covered benefits, and important rules. It is a shorter, easier-to-read version of the Evidence of Coverage.

A level in a Part D formulary that determines how much you pay for a drug. Most plans have 4–5 tiers. Generic drugs are typically in lower tiers with lower copays; brand-name and specialty drugs are in higher tiers with higher copays or coinsurance.

The amount that counts toward moving you through Medicare Part D phases and into catastrophic coverage. TrOOP includes what you pay out of pocket for covered Part D drugs, plus certain payments made on your behalf.

Processes used by Medicare Advantage and Part D plans to ensure services and drugs are medically appropriate and used efficiently. Includes prior authorization, step therapy, and quantity limits.

The process of using your ZIP code to find Medicare Advantage or Part D plans available in your area. Plan availability, provider networks, and premiums can vary significantly based on your geographic location.