Medicare Explained: Parts A, B, C and D, Costs, Deadlines and Your Options

In short: Medicare is the federal health insurance program for people 65 and older and for some younger people with disabilities or permanent kidney failure. The government runs Original Medicare. Private insurance companies approved by Medicare offer the plans that add to it or replace it.

Medicare is administered by the Centers for Medicare and Medicaid Services, known as CMS, which is part of the U.S. Department of Health and Human Services. CMS sets the rules for the program, approves private plans and publishes the yearly cost figures. The Social Security Administration handles the enrollment side: it takes Medicare applications, collects Part B premiums from Social Security checks, and decides whether higher income earners owe an added amount. Medicare.gov is the official website where you compare plans and look up your coverage.

That split matters because people often call the wrong office. For questions about signing up, premiums taken from your Social Security check, or a replacement Medicare card, Social Security is the place. For questions about what a specific plan covers, comparing plans, or your claims, Medicare.gov, 1-800-MEDICARE and the plan itself are the places. For help choosing among plans in your county and enrolling in the one that fits, that is where a licensed agent like me comes in.

Medicare is not one policy. It is a set of parts, each covering different services, and you decide how to combine them. The two big decisions are whether to stay with Original Medicare and add a supplement and a drug plan, or to choose a Medicare Advantage plan that bundles everything. The rest of this page walks through each piece so you can see how the decision works before you talk to anyone.

Sources: Medicare.gov basics and CMS Medicare overview.

In short: Part A covers hospital care. Part B covers doctors and outpatient care. Part C, also called Medicare Advantage, is a private plan that bundles A and B and usually D. Part D covers prescription drugs.

Together, Part A and Part B are called Original Medicare. If you stay with Original Medicare, you can go to any doctor or hospital in the country that accepts Medicare. Because Original Medicare has no cap on yearly spending and covers only part of the cost, most people add a Medigap plan, a Part D drug plan, or choose Medicare Advantage instead. You cannot do both: a Medigap policy cannot be used with a Medicare Advantage plan.

Part C is the most misunderstood name. It is not a new government benefit. It is a different way to receive your Part A and Part B benefits through a private company. You still have Medicare, you still pay your Part B premium, and the plan must cover at least what Original Medicare covers. What changes is how you use it: the network, the copays and the extras.

Sources: Medicare.gov plan options, Medicare.gov Medigap and Medicare.gov drug coverage.

In short: You qualify at 65 if you or your spouse paid Medicare taxes for about 10 years. You can qualify earlier if you receive Social Security Disability benefits for 24 months or have permanent kidney failure or ALS.

Eligibility is not the same as enrollment. Becoming eligible means you are allowed to join. Whether you are enrolled automatically or must sign up yourself depends on whether you already receive Social Security or Railroad Retirement benefits. If you do, you are generally enrolled in Parts A and B at 65 and your card arrives in the mail about three months before your birthday month. If you do not, you apply through Social Security, which allows you to apply online, by phone or in person at a local office.

When you apply, Social Security asks for your Social Security number, your place of birth, and the start and end dates of any group health coverage you have had through work. If you are signing up for Part B only, you also need a valid email address and your Medicare number. Having these ready makes the process take minutes.

Sources: Social Security: sign up for Medicare and Medicare.gov: get started.

In short: Your Initial Enrollment Period is seven months: the three months before your 65th birthday month, your birthday month, and the three months after. Missing it can mean lifelong penalties, so mark the date.

Medicare.gov notes that coverage always starts on the first day of a month. That detail has a real effect on timing. If your birthday falls on the first of the month, your coverage starts the month before. A person who signs up too late in the window can end up with a gap between a retiring employer plan and the start of Medicare.

The most common trap involves people who keep working past 65. If you or your spouse have group health coverage from a current employer, you can often delay Part B without a penalty, and then use a Special Enrollment Period when that coverage ends. Coverage through COBRA or retiree plans, however, generally does not count as current employment for this purpose, according to Medicare.gov. Many people have been surprised by that rule, and the penalty applies for as long as they have Part B.

A practical habit: three months before your 65th birthday, call me or Social Security, confirm whether you are being enrolled automatically, and ask your employer’s benefits office in writing whether your plan counts as creditable coverage for Medicare. That written answer protects you.

Sources: Medicare.gov: when coverage starts and Social Security: sign up. Annual Enrollment and Medicare Advantage Open Enrollment dates are published by CMS and Medicare.gov each year.

In short: Most people pay no Part A premium. The standard Part B premium is $202.90 a month in 2026, with a $283 yearly deductible. Part A has a $1,736 deductible for each benefit period.

These amounts change every year, and the next set is typically announced in the fall. Plan premiums for Medicare Advantage, Part D and Medigap are set by the insurance companies and vary by plan and by county, which is why two neighbors can pay different amounts for similar coverage.

Here is a simple way to see what these numbers mean together. With Original Medicare alone and no supplement, a single hospital admission could cost you the Part A deductible, plus 20 percent of every doctor bill during your stay. A bad year with several hospital stays has no cap under Part A and Part B. That exposure is the reason most people add a Medigap plan or choose a Medicare Advantage plan, which carries a yearly out-of-pocket limit.

Higher income? You may pay an added amount (IRMAA)

Social Security looks at your income from two years ago to decide whether you owe an Income-Related Monthly Adjustment Amount, called IRMAA, on top of the standard Part B and Part D premiums. For 2026 premiums, that is generally your 2024 tax return. The amounts added each month in 2026, according to Social Security, are below.

If your income dropped because of a life-changing event, you can ask Social Security for a new decision using Form SSA-44. Qualifying events include marriage, divorce, the death of a spouse, stopping work or reducing hours, and the loss of income-producing property due to a disaster. You will need documents showing the event and the lower income. You do not need to file a formal appeal for this type of request.

Sources: Medicare.gov: Medicare costs, Social Security: Medicare premiums and CMS 2026 rate announcement. Amounts shown are for 2026 and are rounded as published.

In short: Waiting to sign up for Part B or Part D without qualifying coverage can add a penalty that lasts as long as you have Medicare. Most people can avoid both by enrolling on time or documenting creditable coverage.

Creditable drug coverage means the drug coverage you had was expected to pay, on average, at least as much as Medicare’s standard drug coverage. Your employer, union or former plan sends a notice every year saying whether your coverage is creditable. Keep that notice. It is the document that protects you from a Part D penalty if you enroll later.

Source: Medicare.gov: avoid penalties.

In short: There is no single best choice. Original Medicare plus Medigap and Part D gives you freedom to see any Medicare doctor and predictable costs for a higher premium. Medicare Advantage often has a lower premium and extra benefits in exchange for networks and approval rules.

The most useful way to decide is to start with your real life, not the brochure. Ask four questions. Which doctors and hospitals do you want to keep? Which prescriptions do you take, and are they covered by the plan you are considering? How much of the year do you spend away from home? And would you rather pay a higher premium for predictability, or a lower premium and take some chance on a bad year?

Medicare.gov points out that Medicare Advantage plans are offered by private companies that must follow Medicare’s rules, and that insurers decide whether a plan is available statewide or only in certain counties. Plans can also enter or leave Medicare each year. That is why a local review matters: the plan that was best for you last year may not be the best choice, or even available, this year.

Source: Medicare.gov: your health plan options.

In short: Medigap is private insurance that helps pay what Original Medicare leaves behind: copayments, coinsurance and deductibles. The best time to buy one is during your six month Medigap Open Enrollment Period.

According to Medicare.gov, you generally need both Part A and Part B before you can buy a Medigap policy. The plans are standardized by letter, so a Plan G sold by one company provides the same basic benefits as a Plan G sold by another. What differs is the price and the company behind it. That makes comparing Medigap simpler than comparing Medicare Advantage: you compare price, financial strength and service, because the benefits are the same.

Your Medigap Open Enrollment Period starts the month you are 65 or older and enrolled in Part B, and it lasts six months. During that window, companies generally cannot turn you down or charge more because of your health. After it ends, in most states a company can ask health questions and may decline you. That is the single most important timing rule for people who plan to go this route. If you start in Medicare Advantage and later want a Medigap plan, you may have to answer health questions, depending on your state and situation.

Medigap does not include drug coverage. You add a separate Part D plan. It also does not include dental, vision or hearing. If those matter to you, ask about standalone plans. And because Medigap works only with Original Medicare, you cannot use it with a Medicare Advantage plan.

Source: Medicare.gov: Medigap. Medigap Open Enrollment details and plan lettering are also explained in Medicare.gov’s Medigap guide.

In short: Part D is optional but important. Joining late can trigger a lifetime penalty, and in 2026 your yearly out-of-pocket spending on covered drugs is capped at $2,100.

Medicare.gov describes Part D as optional coverage offered by private insurers and other companies approved by Medicare, helping pay for both brand name and generic drugs. It advises getting coverage even if you do not take drugs now, because joining later can mean a penalty.

CMS reports that in 2026 enrollees reach the catastrophic phase once their yearly out-of-pocket spending reaches $2,100, after which they pay nothing more for covered drugs that year. CMS also notes that every Part D plan sponsor must offer the Medicare Prescription Payment Plan, which lets you spread out-of-pocket drug costs across the year instead of paying them all at the pharmacy. For insulin, CMS describes a 2026 cost-sharing limit of the lesser of $35 for a month’s supply or a percentage of the negotiated or maximum fair price.

Every plan has its own formulary, which is the list of drugs it covers, along with pharmacies it prefers and the tier each drug falls into. Two plans can cover the same drug at very different prices. The plan with the lowest premium is often not the plan with the lowest total cost for your medicine. That is why I enter your exact medications and your pharmacy before recommending a plan.

If you have limited income and resources, ask about Extra Help, a program that can reduce drug plan premiums and costs, and about Medicare Savings Programs, which can help pay your Part B premium. Social Security and your state Medicaid office handle those applications, and I can point you to the right place.

Sources: Medicare.gov: Part D and CMS 2026 rate announcement fact sheet.

In short: Medicare Advantage can be a good fit, especially if you want extras and a lower premium. The risk is choosing on the benefits list alone and discovering later that your doctor or medicine is not covered.

Also remember that Medicare Advantage can affect other coverage. Medicare.gov warns that joining a Medicare Advantage plan may end your employer or union coverage, and that loss may extend to your spouse and dependents. Always check with your benefits office before switching.

If a plan you are in leaves Medicare or your county, you must join another Medicare health plan or return to Original Medicare, with a Special Enrollment Period to do so. Plans can also disenroll you for reasons such as moving out of the service area. The right response to those notices is to act early, not wait until January.

Source: Medicare.gov: your health plan options.

In short: Medicare plans change every year. Each fall, your plan sends an Annual Notice of Change and Evidence of Coverage that explain next year’s premiums, copays, drug list and network. Reading it is the cheapest way to avoid a surprise.

The Annual Enrollment Period runs from October 15 to December 7. During those weeks you can switch from one Medicare Advantage plan to another, move between Original Medicare and Medicare Advantage, join or change a Part D plan, and add or drop drug coverage. Whatever you choose takes effect on January 1. If you are happy with your plan and its changes, you do not have to do anything, but the plan you have is not guaranteed to be the best plan for the new year.

Here is the checklist I use with clients each fall. First, read the notice of changes from your current plan and note any change to premiums, deductibles, copays, the out-of-pocket limit and your drug tiers. Second, confirm your doctors and hospitals are still in network. Third, re-enter your medications in the Medicare plan finder or send them to me. Fourth, compare at least the lowest-cost alternative and the plan most similar to yours. Fifth, decide by early December so there is time to fix any problem.

If you are already enrolled in a Medicare Advantage plan and your January experience disappoints you, the Medicare Advantage Open Enrollment Period, January 1 to March 31, gives you one chance to switch to a different Advantage plan or return to Original Medicare and add a Part D plan. It does not allow you to change from Original Medicare into Medicare Advantage; that happens during Annual Enrollment.

Sources: CMS and Medicare.gov publish the enrollment calendar each year. Your plan’s notices are the authoritative source for your own plan.

In short: I compare the plans I represent in your county, check your doctors and medications, explain what you will pay, help you enroll, and stay available all year. It costs you nothing, because insurance companies pay agents, and your premium is the same.

In short: Medicare rules are national, but the plans, prices and doctors are local. Choose your state to see the county guides, then pick your county for local plan and provider information.

Plan availability depends on where you live. We are licensed in the states listed in the disclaimer at the bottom of this page, and we do not offer every plan available in your area.

• Medicare.gov: Medicare costs (2026 premiums, deductibles and coinsurance)
• Medicare.gov: when does Medicare coverage start (enrollment periods)
• Medicare.gov: avoid late enrollment penalties
• Medicare.gov: your health plan options
• Medicare.gov: Medigap (Medicare Supplement Insurance)
• Medicare.gov: Medicare drug coverage (Part D)
• CMS: 2026 Medicare Advantage and Part D rate announcement fact sheet
• Social Security Administration: sign up for Medicare
• Social Security Administration: Medicare premiums and income-related amounts

REMCARE Insurance Agency is not connected with or endorsed by the U.S. government or the federal Medicare program. This page is general information, not a guarantee of coverage or advice about your specific situation. Figures are the published 2026 amounts; check Medicare.gov for the newest numbers.