Medicare Part C and Part D are two different add-ons to Original Medicare
Medicare Part C (also called Medicare Advantage) is an alternative way to get your Part A and Part B coverage through a private insurance company instead of the government. Medicare Part D is prescription drug coverage you add to Original Medicare or Part C. They are separate programs with different purposes, different costs, and different enrollment windows.
Part C replaces your hospital and medical coverage entirely. Part D only covers medications. You can have Part C without Part D if your plan includes drug coverage, or you can have Original Medicare with Part D added. The choice between them depends on your doctors, your medications, and what you can afford to pay out of pocket.
Key Takeaways
- Medicare Part C is sold by private insurers and covers hospital, doctor, and usually prescription drugs all in one plan, while Part D is prescription drug coverage only and works with Original Medicare.
- Part C plans have networks of doctors and hospitals you must use, while Original Medicare lets you see any doctor who accepts Medicare.
- Part D plans vary widely in which drugs they cover and how much you pay, so comparing plans each year can save you hundreds of dollars on medications.
- You can change Part C or Part D plans once a year during the annual enrollment period, which runs from October 15 to December 7.
How Medicare Part C works and who it is for
Part C is a complete replacement for Original Medicare (Part A and Part B). When you join a Part C plan, you stop using your red, white, and blue Medicare card for hospital and doctor visits. Instead, you use the insurance card from the private company running the plan. The plan itself pays for hospital stays, doctor visits, and usually preventive care, just as Original Medicare does.
Part C plans are run by companies like UnitedHealthcare, Humana, Anthem, and Aetna. Each plan has its own network of doctors and hospitals. If you see a doctor outside the network, you pay more or the plan does not cover the visit at all. This is the biggest trade-off: Part C plans often cost less in monthly premiums than Original Medicare plus a Medigap policy, but you lose the freedom to see any doctor.
Part C plans must cover everything Part A and Part B cover, but they can add extra benefits. Many plans include dental, vision, hearing aids, or gym memberships. Some plans have $0 monthly premiums. However, you still pay the Part B premium to Medicare, and you may pay copays or coinsurance when you use the plan.
How Medicare Part D works and what it covers
Part D covers prescription drugs only. It does not cover doctor visits, hospital stays, or medical equipment. If you have Original Medicare, you add Part D as a separate plan. If you have Part C, your plan may already include drug coverage, but you can switch to a standalone Part D plan if you want different drugs covered.
Part D plans are also run by private insurers. Each plan has a formulary — a list of drugs it covers. The same drug may be covered by one plan but not another, or covered at different prices. This is why comparing plans matters: your current medications may cost $50 a month on one plan and $200 on another.
Part D has a coverage gap, sometimes called the "donut hole." Once you and your plan have spent $5,380 on covered drugs in 2024 (this amount changes each year), you enter the gap and pay a higher percentage of drug costs until you reach $7,820 in total spending. After that, you pay a small copay for the rest of the year. The exact amounts and percentages shift annually, so check your plan's details each year.
Part C versus Original Medicare with Medigap
Part C is not the only way to add coverage to Medicare. You can also keep Original Medicare and buy a Medigap policy (supplemental insurance) from a private company. Medigap covers the copays, coinsurance, and deductibles that Original Medicare does not. The difference is that Medigap lets you see any doctor who accepts Medicare, while Part C limits you to a network.
Part C plans often have lower or no monthly premiums, but you pay copays when you use the plan. Medigap has a monthly premium, but once you meet the deductible, you typically pay little or nothing at the doctor or hospital. If you see many specialists or travel frequently, Medigap may cost less overall. If you are healthy and do not mind a network, Part C may be cheaper.
You cannot have both Part C and Medigap at the same time. If you switch from Part C to Original Medicare, you can buy Medigap, but the insurance company can charge you more if you have pre-existing conditions, depending on your state. If you switch from Original Medicare with Medigap to Part C, you lose the Medigap coverage.
When you can enroll in Part C or Part D
You first become may be able to access for Part C and Part D when you turn 65 and sign up for Medicare Part A and Part B. You have a seven-month window called your Initial Enrollment Period. If you miss this window, you can still join during the Annual Enrollment Period, which runs from October 15 to December 7 each year. Coverage starts January 1.
If you do not join Part D when you first become may be able to access and you do not have other drug coverage, you may pay a late enrollment penalty. The penalty is about 1% of the national average Part D premium for each month you were without coverage. This penalty stays with you for life, so joining on time matters.
You can change Part C or Part D plans once per year during the Annual Enrollment Period. You can also switch plans if you move out of your plan's service area, lose your current coverage, or may have access to for a Special Enrollment Period due to a major life event like losing employer coverage.
What Part C and Part D cost
Part C plans have varying costs. Some have $0 monthly premiums, but you still pay your Part B premium to Medicare. Others charge $50 to $200 or more per month. When you use the plan, you pay copays (a set amount per visit) or coinsurance (a percentage of the cost). The copay for a doctor visit might be $15 to $50, depending on the plan.
Part D plans also vary. A basic plan might cost $5 to $15 per month, while more comprehensive plans cost $30 to $100 per month. Your actual drug costs depend on which tier your medications fall into. Tier 1 drugs (generics) might cost $5 to $10 per prescription, while Tier 4 or 5 drugs (brand names) can cost $50 to $200 or more.
You pay nothing out of pocket for preventive services like annual wellness visits, cancer screenings, and vaccinations under both Part C and Part D. However, if you need treatment after a preventive screening, you pay according to your plan's copays and deductibles.
How to compare Part C and Part D plans
Medicare provides a plan comparison tool at Medicare.gov. You enter your zip code, your current medications, and your preferred doctors. The tool shows you which Part C plans include those doctors and which Part D plans cover your drugs at the lowest cost. You can also call 1-800-MEDICARE to speak with someone who can walk you through the comparison.
When comparing Part C plans, check whether your doctors and hospitals are in the network. Ask whether you need a referral to see a specialist. Look at the copays for the services you use most. If you take many medications, compare the formularies and out-of-pocket costs across Part D plans, not just the monthly premium.
Many people assume the cheapest plan is the best deal, but the lowest premium may have high copays or exclude your doctors. Spending an hour comparing plans can save you hundreds of dollars per year. You can change plans every year, so if your situation changes — you switch doctors, start a new medication, or move — you can switch plans at the next enrollment period.
Common mistakes to avoid
The most common mistake is not joining Part D on time. If you delay and do not have other drug coverage, you will pay a penalty for life. The second mistake is not updating your plan choice each year. Your medications change, drug prices change, and plan networks change. A plan that was perfect last year may not be the best choice this year.
Another mistake is assuming your doctor is in a Part C network without checking. Call the plan or use its website to confirm before you enroll. If your doctor is not in the network and you enroll anyway, you will have to pay out of pocket or switch plans.
Finally, do not confuse Part C with Part D. Part C is hospital and doctor coverage. Part D is drugs only. If you have Part C with drug coverage, you do not need a separate Part D plan. If you have Original Medicare, you need Part D if you want prescription drug coverage.
Frequently Asked Questions
Can I have both Part C and Part D?
Yes. If your Part C plan includes drug coverage, you do not need Part D. If your Part C plan does not include drugs, you can add a standalone Part D plan. You cannot have two Part D plans at the same time, but you can switch from one to another during the annual enrollment period.
What happens if I do not join Part D when I turn 65?
You can join later, but you will pay a late enrollment penalty of about 1% of the national average Part D premium for each month you were without coverage. This penalty is added to your monthly premium for life, even if you switch plans later. The only exception is if you had other drug coverage during that time.
Can I switch from Part C back to Original Medicare?
Yes, during the Annual Enrollment Period from October 15 to December 7, or if you may have access to for a Special Enrollment Period. If you switch back to Original Medicare, you can buy a Medigap policy, but the insurance company may charge you more if you have pre-existing conditions, depending on your state.
Do Part C plans cover everything that Original Medicare covers?
Part C plans must cover everything Part A and Part B cover, including hospital stays, doctor visits, and preventive care. However, they may have different copays, deductibles, and networks than Original Medicare. Some services may require prior approval from the plan before you receive them.
How do I know if my medications are covered by a Part D plan?
Each Part D plan publishes a formulary listing the drugs it covers. You can search the formulary on the plan's website or call the plan directly. You can also use the Medicare plan comparison tool at Medicare.gov, which shows you the cost of your specific medications under each plan in your area.