Original Medicare Explained: Parts A, B, C and D

Original Medicare is the federal health insurance program run by the government: Part A for hospital care and Part B for doctor and outpatient care. As Jackie puts it on her original Medicare page, Medicare is made up of four parts, but at any given time you will only be using either Part A, Part B and Part D, or you will be using Part C. Parts A and B pay first, Part D adds prescription drug coverage from a private plan, and a Medicare Supplement (Medigap) can pick up most of what A and B leave behind. Part C, Medicare Advantage, is the private-plan alternative that takes the place of that whole bundle. This guide walks through each part, with the 2026 costs CMS has published, so you can see where the gaps are before you choose how to fill them.

The four parts at a glance

Source: Medicare.gov: What does Medicare cover?.

Part A: hospital insurance

Part A covers inpatient hospital stays, care in a skilled nursing facility after a qualifying hospital stay, hospice care and some home health care. Most people pay no monthly premium for it, which Medicare calls premium-free Part A, because they or a spouse paid Medicare taxes for at least 40 quarters (about 10 years) while working. If you have fewer quarters, you can buy Part A: in 2026 the premium is $311 a month with 30 to 39 quarters and $565 a month with fewer than 30 (CMS).

Part A has a large deductible when you use it: $1,736 for each benefit period in 2026. A benefit period starts the day you are admitted and ends when you have been out of the hospital or a skilled nursing facility for 60 days in a row, so one person can pay the deductible more than once in a year. After the deductible, Part A pays covered hospital costs for the first 60 days of a stay. Longer stays bring daily coinsurance, and skilled nursing care has a daily coinsurance after the first 20 days.

Part B: medical insurance and the 80/20 split

Part B is outpatient medical coverage. It helps pay for medically necessary services you need to diagnose and treat a condition: visits to your primary care doctor and specialists, outpatient surgery, lab work, X-rays and scans, durable medical equipment such as a walker or oxygen, ambulance trips and many preventive services.

In 2026 the standard Part B premium is $202.90 a month and the yearly deductible is $283 (CMS). After you meet the deductible, Medicare generally pays 80 percent of the Medicare-approved amount and you pay the other 20 percent. That 80/20 split is the heart of the gap: there is no yearly limit on your 20 percent in Original Medicare, so a cancer treatment, a joint replacement or a long series of outpatient infusions can leave a very large bill.

If you already receive Social Security or Railroad Retirement benefits, the Part B premium is taken out of your monthly check. If not, Medicare sends you a bill, usually every three months, and you can pay it through your Medicare account online, through Medicare Easy Pay (an automatic deduction from your bank account), through your bank's online bill pay, or by mail (Medicare.gov). People with higher incomes pay more for Part B; our IRMAA guide explains the 2026 brackets.

Part C: Medicare Advantage

Part C, also called Medicare Advantage (you may see MA, or MAPD when it includes drug coverage), is an alternative way to get your Medicare benefits. It is offered by private insurance companies approved by Medicare, so you do not enroll in it at the Social Security office. You sign up with the plan, usually with help from an agent like Jackie or through Medicare.gov.

Most plans are network plans, such as HMOs and PPOs, with copays and coinsurance for services and a yearly in-network out-of-pocket maximum. When you join one, the plan becomes the insurer you use for your care and your red, white and blue Medicare card goes in a drawer, but you are still in Medicare and you keep paying your Part B premium. Many plans include Part D drug coverage and extras such as dental, vision or hearing benefits.

In Camden County for 2027 there are 41 Medicare Advantage plans from 10 organizations, not counting Special Needs Plans, with in-network out-of-pocket maximums from $4,150 to $9,850 (CMS CY2027 Landscape, via THE BRAIN).

Part D: prescription drug coverage

Part D is prescription drug coverage, sold by private companies approved by Medicare. You can get it as a standalone drug plan (often written PDP) alongside Original Medicare, or built into a Medicare Advantage plan. New Jersey has 11 standalone Part D plans for 2027, with premiums from $5.30 to $217.90 a month (CMS CY2027 Landscape, New Jersey PDP region).

Part D is not legally required, but it works like it is. If you go 63 days or more in a row without Part D or other creditable drug coverage (coverage at least as good as Medicare's standard benefit, such as many employer plans) after your first chance to enroll, Medicare adds a late enrollment penalty to your premium for as long as you have Part D. That is why Jackie tells clients to line up drug coverage the day Medicare starts, even if they take few prescriptions today.

What Original Medicare does not cover

Original Medicare leaves out several things people assume are included (Medicare.gov):

• Routine dental care, cleanings and dentures.
• Eye exams for glasses, and eyeglasses or contact lenses (with a limited exception after cataract surgery).
• Hearing aids and the exams for fitting them.
• Long-term custodial care, the help with bathing, dressing and eating that many people need in a nursing home or at home.
• Most care outside the United States.
• Retail prescription drugs, unless you add Part D.

How a Medicare Supplement and Part D fill the gaps

A Medicare Supplement, also called Medigap, is sold by private companies to help pay the out-of-pocket costs Original Medicare leaves behind. Medicare pays its share first; then the supplement pays its share, up to the plan's limits. Plans are standardized by letter. Plan G, for example, pays the Part A deductible, the 20 percent Part B coinsurance, Part B excess charges and skilled nursing coinsurance, leaving you only the Part B deductible ($283 in 2026).

A supplement does not include drug coverage, so the usual pairing is Original Medicare plus a supplement plus a standalone Part D plan. That gives you two or three monthly premiums, and in return you can use any doctor or hospital in the country that accepts Medicare, with very predictable costs when you get care.

Illustration: a hypothetical example built from the rules and figures cited on this page, not a quote.

The two paths, side by side

Every Medicare decision comes back to the choice Jackie describes on her own site: Original Medicare with a supplement and a drug plan, or a Medicare Advantage plan. The first path costs more each month and gives you broad access and predictable bills. The second usually costs less each month and uses networks, copays and a yearly maximum. Our guide to Medicare Advantage versus Medicare Supplement compares them in detail, including why the order you choose them in matters in New Jersey.

• Path 1: Part A + Part B + a Medicare Supplement + a Part D plan.
• Path 2: Part A + Part B, received through a Medicare Advantage (Part C) plan that usually includes Part D.

What Jackie checks for you

• Whether you will get premium-free Part A, and whether you need Part B right away or can delay it because of coverage from current work.
• How your Part B premium will be paid, and whether your income puts you in an IRMAA bracket.
• Your doctors, hospital and prescriptions, so both paths are priced on your real care.
• The supplement premiums for your age and ZIP code, and the 2027 Medicare Advantage and Part D plans in your county.
• Your deadlines, so nothing triggers a late enrollment penalty.

Questions to ask yourself

• Do I want to keep specific doctors or hospitals, including ones outside New Jersey?
• Would I rather pay more each month for predictable bills, or less each month with copays up to a yearly maximum?
• Which prescriptions do I take, and which pharmacy do I use?
• Do dental, vision or hearing benefits matter enough to shape my choice?
• Am I still working with group coverage, or retiring?

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The bottom line

Original Medicare is Part A for the hospital and Part B for doctors and outpatient care, with a 20 percent share and no yearly limit. Most people fill that gap one of two ways: a Medicare Supplement plus a Part D drug plan, or a Medicare Advantage plan. Jackie can lay out both for your doctors, drugs and budget at no cost, by phone, Zoom or in person: call or text (856) 727-4221.