When you first approach Medicare eligibility, the alphabet soup of Part A, Part B, Part C, and Part D can feel overwhelming. You're not alone — millions of Americans find themselves confused by a system that should be straightforward.
This guide cuts through the complexity. By the end, you'll know exactly what each Medicare part covers, what you'll pay out of pocket, and — critically — the enrollment deadlines that can cost you money if you miss them.
Part A = Hospital coverage. Part B = Doctor visits & outpatient care. Part C = Medicare Advantage (private alternative to A+B). Part D = Prescription drugs. Most people pay $0 for Part A, and $174.70/month for Part B in 2026.
Medicare Part A: Hospital Insurance
Part A is your hospital insurance. It covers inpatient care at hospitals, skilled nursing facility care after a hospital stay, hospice care, and some home health services.
What Part A covers
- Inpatient hospital stays (semi-private room, meals, nursing care, medications)
- Skilled nursing facility care — but only after a 3-day qualifying hospital stay
- Hospice care for the terminally ill
- Limited home health care if you're homebound and need skilled nursing or therapy
What you pay for Part A in 2026
Most people pay $0 in monthly premiums for Part A if they or their spouse worked and paid Medicare taxes for at least 10 years (40 quarters). If you haven't worked enough quarters, you may pay up to $518/month in 2026.
However, Part A is not entirely free when you use it. You'll face a $1,632 deductible per benefit period in 2026. After that, there are coinsurance costs for longer hospital stays.
Medicare Part B: Medical Insurance
Part B is your outpatient medical insurance — the part that covers your doctor visits, preventive care, lab tests, and most medical equipment.
What Part B covers
- Doctor visits and specialist appointments
- Outpatient hospital services
- Preventive care (annual wellness visits, flu shots, mammograms, colonoscopies)
- Lab tests, X-rays, and diagnostics
- Durable medical equipment (wheelchairs, walkers, CPAP machines)
- Mental health services
- Some home health services
What you pay for Part B in 2026
The standard Part B premium in 2026 is $174.70 per month. If your income exceeds certain thresholds, you'll pay an Income-Related Monthly Adjustment Amount (IRMAA) surcharge on top of that.
After paying the annual deductible ($240 in 2026), Medicare pays 80% of approved costs and you pay the remaining 20% — with no out-of-pocket cap. This is why many people add a Medigap (supplemental) plan.
Medicare Part C: Medicare Advantage
Medicare Advantage (Part C) is an alternative way to receive your Medicare benefits through a private insurance company that contracts with Medicare. Instead of getting Part A and Part B separately, you bundle them — and usually Part D — into one plan.
Key characteristics of Medicare Advantage
- Offered by private insurers approved by Medicare
- Must cover everything Original Medicare (Parts A and B) covers
- Usually includes drug coverage (Part D)
- Often includes extras: dental, vision, hearing aids, gym memberships
- Typically works as an HMO or PPO — you may need referrals and must use network providers
Medicare Advantage can look attractive because of low or $0 premiums and added benefits. But if you travel frequently, live part of the year in another state, or have complex health needs requiring specialists, Original Medicare + Medigap often works out better. Always compare total out-of-pocket maximums, not just premiums.
Medicare Part D: Prescription Drug Coverage
Part D is standalone prescription drug coverage. It's offered by private insurance companies and helps pay for outpatient prescription medications. You can add Part D to Original Medicare (Parts A and B), or it may be bundled into your Medicare Advantage plan.
How Part D works
Part D plans use a formulary — a list of covered drugs organized into tiers. Generic drugs are on lower tiers with lower copays; brand-name and specialty drugs are on higher tiers with higher costs.
In 2026, a major change makes Part D more affordable: the annual out-of-pocket cap is now $2,000. Once you hit this cap, you pay nothing more for covered drugs for the rest of the year.
Critical Enrollment Windows You Cannot Miss
Missing Medicare enrollment deadlines can result in permanent premium penalties that follow you for life. Here are the windows you need to know:
Initial Enrollment Period (IEP)
Your IEP is a 7-month window: the 3 months before your 65th birthday, your birthday month, and 3 months after. This is your primary opportunity to enroll without penalty.
Special Enrollment Period (SEP)
If you have employer coverage when you turn 65, you can delay Medicare without penalty. When that employer coverage ends, you get an 8-month SEP to enroll in Part B without penalty.
Late enrollment penalties
- Part B penalty: 10% added to your premium for every 12-month period you were eligible but didn't enroll — and this penalty is permanent
- Part D penalty: 1% of the national base beneficiary premium for each month you went without coverage — also permanent
- Part A penalty (if you have to pay): 10% higher premium for twice the number of years you were eligible but didn't enroll
Original Medicare vs. Medicare Advantage: Which Is Better?
This is the most common question — and there's no universal answer. It depends on your health needs, finances, and lifestyle.
Original Medicare (Parts A + B + Medigap + Part D) is generally better if you want the widest choice of doctors and hospitals, travel frequently, have complex health conditions, or want predictable costs.
Medicare Advantage may be better if you want one-card simplicity, appreciate extra benefits (dental, vision), have predictable healthcare needs, and are comfortable staying within a provider network.
You can switch from Medicare Advantage back to Original Medicare during the Medicare Annual Enrollment Period (October 15 – December 7 each year). However, if you switch after age 65, Medigap insurers in most states can deny you coverage or charge higher rates based on health conditions.
Your Next Steps
Now that you understand the four parts of Medicare, here's what to do:
- Check your enrollment window. Visit ssa.gov or call 1-800-MEDICARE to confirm your Initial Enrollment Period dates.
- Compare plans. Use the Medicare Plan Finder at medicare.gov to compare Part D and Medicare Advantage plans in your area.
- Consider your Medigap options early. If you choose Original Medicare, the best time to buy a Medigap policy is during your 6-month Medigap Open Enrollment Period (starts when you're 65 and enrolled in Part B).
- Get free help. Every state has a State Health Insurance Assistance Program (SHIP) that offers free, unbiased Medicare counseling. Find yours at shiphelp.org.