Key Takeaways
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Medicare is divided into four main parts: A, B, C, and D. Each part covers a specific aspect of your healthcare needs, and understanding how they interact is essential to making informed coverage decisions.
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You may not need all parts at once. Some are automatic when you turn 65, others require active enrollment based on your circumstances.
The Framework of Medicare in 2025
Medicare is not a single plan. It’s a federally funded health insurance program designed primarily for people age 65 and older, although certain younger individuals with disabilities or specific health conditions also qualify. As of 2025, over 65 million Americans rely on Medicare in some form.
To understand your options and responsibilities, you need to see how each part of Medicare fits into the broader picture of your healthcare needs. Each part is tailored to a specific type of coverage, and while they function independently, they often work together to provide full protection.
What Part A Covers
Part A is hospital insurance. You’re generally eligible for premium-free Part A if you or your spouse paid Medicare taxes for at least 10 years (40 quarters).
It typically includes coverage for:
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Inpatient hospital stays
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Skilled nursing facility care (after a qualifying hospital stay)
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Hospice care
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Some home health care services
In 2025, the Part A deductible is $1,676 per benefit period. After that, Medicare pays a portion of the costs based on the number of days you’re hospitalized.
Most people are automatically enrolled in Part A at age 65 if they’re receiving Social Security or Railroad Retirement Board benefits.
Understanding Part B
Part B covers outpatient medical services. This includes a wide range of healthcare needs that don’t require a hospital stay.
Covered services under Part B:
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Doctor visits and specialist consultations
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Preventive services (like vaccines and screenings)
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Outpatient surgeries and procedures
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Durable medical equipment (DME)
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Mental health services
In 2025, the standard Part B premium is $185 per month, and the deductible is $257 annually. Once the deductible is met, you typically pay 20% of the Medicare-approved amount for most services.
Enrollment in Part B is optional, but if you delay enrollment without having other creditable coverage, you could face a late enrollment penalty that continues for life.
What Makes Part C Different
Part C refers to Medicare Advantage. This is an alternative way to receive your Medicare benefits through a private plan that is approved by Medicare. It combines coverage from Parts A and B and often includes additional services.
A Medicare Advantage plan typically includes:
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All services covered under Parts A and B
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Extra benefits like dental, vision, and hearing (varies by plan)
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Prescription drug coverage (most plans include it)
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Care coordination and wellness programs
You must be enrolled in both Part A and Part B to join a Medicare Advantage plan. Since these are offered by private companies, costs, provider networks, and benefits can vary significantly. Plans must cover everything Original Medicare covers but may do so with different cost structures and service rules.
Where Part D Comes In
Part D is your prescription drug coverage. It is optional but highly recommended if you take medications regularly.
You can get Part D in one of two ways:
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As a standalone plan with Original Medicare (Parts A and B)
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As part of a Medicare Advantage plan that includes drug coverage
In 2025, the Part D deductible can be up to $590. After you meet the deductible, you enter the initial coverage phase where you pay a share of the drug costs.
A major improvement in 2025 is the new $2,000 out-of-pocket cap on Part D spending. Once you reach this amount in out-of-pocket costs, your plan covers the rest of your covered medications for the year.
Failing to enroll in Part D when you’re first eligible, without having other creditable coverage, may result in a permanent late enrollment penalty.
How the Parts Work Together
If you stay with Original Medicare, you’ll use:
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Part A for hospital care
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Part B for outpatient and preventive services
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Part D for drug coverage
However, many people choose to combine these under a Part C (Medicare Advantage) plan for simplicity and potentially extra benefits.
You cannot have both a standalone Part D plan and a Medicare Advantage plan that includes drug coverage. You must choose one structure or the other.
Also, neither Part A nor Part B covers most routine dental, vision, or hearing care. These are often only included in Medicare Advantage plans.
Optional Coverage Beyond the Four Parts
Some gaps remain, even if you have all four parts of Medicare.
You may consider:
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Medicare Supplement (Medigap) plans: These help pay for costs like copayments, coinsurance, and deductibles. Available only with Original Medicare (not Medicare Advantage).
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Employer or union retiree coverage: If available, this can wrap around your Medicare coverage to fill gaps.
Neither of these options is part of the official Medicare Parts A-D system, but they can play an important role in your healthcare planning.
Enrollment Timing Matters
You have specific timeframes when you can enroll in each part:
Initial Enrollment Period (IEP)
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Starts 3 months before your 65th birthday
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Ends 3 months after your birthday month (7 months total)
General Enrollment Period (GEP)
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January 1 to March 31 each year
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For those who missed their IEP for Part B or didn’t qualify for a Special Enrollment Period
Annual Enrollment Period (AEP)
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October 15 to December 7
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For changing Part C or Part D plans
Medicare Advantage Open Enrollment Period (MA OEP)
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January 1 to March 31
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For changing your Medicare Advantage plan or returning to Original Medicare
Costs to Consider in 2025
Here’s a summary of general costs you may face:
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Part A: $0 premium (if eligible); $1,676 deductible per benefit period
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Part B: $185 monthly premium; $257 annual deductible; 20% coinsurance after deductible
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Part D: Up to $590 deductible; capped $2,000 annual out-of-pocket
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Part C: Varies by plan; requires Part A and B enrollment
Additional costs may include premiums for Medigap, copayments for specific services, and any uncovered services like dental or vision if not included in your plan.
What You Need to Do Next
Understanding how the parts of Medicare fit together gives you control over your healthcare future. It helps you:
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Choose whether to stick with Original Medicare or explore Medicare Advantage
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Decide if you need drug coverage through Part D
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Consider adding supplemental coverage to fill remaining gaps
Every decision affects your access to care, costs, and peace of mind.
Making Smart Coverage Choices in 2025
Each part of Medicare plays a role—but no single part does it all. By piecing them together properly, you create a system that protects your health, supports your lifestyle, and keeps your budget in check.
If you’re unsure how to fit the parts together based on your medical needs, prescriptions, or provider preferences, it’s worth speaking with a licensed agent listed on this website. They can walk you through your options and help you avoid costly mistakes.
