Medicare Open Enrollment Guide

Medicare open enrollment is a period that runs from October 15 to December 7 every year when anyone with Medicare can switch from Original Medicare to a private Medicare Advantage plan (or vice versa), sign up for or switch between Medicare Part D prescription drug plans, or switch between Medicare Advantage plans. Changes take effect Jan. 1 of the following year.

Key Takeaways

• The Medicare open enrollment period provides an opportunity to make changes to existing Medicare coverage. It runs from Oct. 15 to Dec. 7 each year.
• Individuals enrolled in a Medicare Advantage plan have a separate open enrollment period, Jan. 1 to March 31 each year.
• Any changes made during the fall open enrollment period take effect on Jan. 1 of the following year.
• Changes made to Medicare Advantage Plans take effect on the first day of the month after the request is received.

Medicare Basics

Medicare provides healthcare coverage for many Americans age 65 or older, as well as younger people with certain types of disabilities and medical conditions. Separate parts of Medicare cover particular categories of healthcare services.

Medicare Part A and B

Parts A and B are sometimes called Original Medicare to distinguish them from privately administered Medicare Advantage plans. An estimated 66.4 million people were enrolled in Medicare Parts A and B in 2023.1

Medicare Part A covers inpatient care in a hospital, skilled nursing facility, or nursing home care that’s not required long-term, as well as hospice care and some home healthcare.2 Medicare Part B covers doctor visits, other outpatient services, mental health care, ambulance transport, durable medical equipment, laboratory tests, and preventive screenings.3

Medicare Part C / Medicare Advantage

Medicare Advantage plans are an alternative to original Medicare, offered by private insurance companies under Medicare guidelines. Medicare Advantage is also sometimes called Medicare Part C. It may have lower premiums and deductibles than alternatives, but you often must use in-network providers and get prior authorization for care, which could delay treatment.4

Around 33.8 million, or half of all Medicare recipients, are projected to have a private Medicare Advantage plan in 2024.5

Medicare Part D

Medicare Part D provides prescription drug coverage. You must have traditional Medicare coverage or a Medicare Advantage plan to enroll in Medicare Part D.6

Medigap

Medigap, or Medicare Supplement insurance, is sold by private companies and pays some of the costs Original Medicare doesn’t cover, including deductibles, coinsurance, and copays. To qualify for Medigap, you must have Medicare Parts A and B.7

Medicare does not cover long-term custodial care in a nursing home facility, but Medicaid will in some instances.89

What Can You Change During Medicare Open Enrollment?

During the Medicare open enrollment period, you can make a number of changes to your existing coverage.

Specifically, you can use the Medicare open enrollment window to:

• Switch from Original Medicare (Parts A and/or B) to a Medicare Advantage plan (Medicare Part C)
• Switch from Medicare Advantage to Original Medicare
• Switch, drop, or join a Medicare Advantage plan
• Enroll in, change, or remove Medicare Part D prescription drug coverage10

If you have a Medicare Advantage plan, you can also switch to a different plan during the Medicare Advantage open enrollment period that runs from Jan. 1 to March 31. During this time, you could also opt to switch to Original Medicare and enroll in Medicare Part D.11

Note

New Medicare applicants should sign up during their initial enrollment period, which starts three months before they turn 65 and ends three months after the month they turn 65. If you miss that initial enrollment period, you can sign up during open enrollment.12

Original Medicare vs. Medicare Advantage

One of the biggest questions you might have during open enrollment is whether it makes sense to choose original Medicare or a Medicare Advantage plan. Understanding the coverage options and costs can help you decide which one makes more sense for you.

Here’s an overview of how the two compare.

Original Medicare vs. Medicare Advantage Plans

Original Medicare

• Use any doctor, hospital, or healthcare provider enrolled in Medicare and accepting new Medicare patients.
• Medicare Parts A and B coverage.
• No primary care doctor required, and no referrals to see a specialist.
• Pay a deductible, co-pays or co-insurance, along with premiums for Medicare Part B.
• Medicare Part D coverage is not included.

Medicare Advantage

• Use doctors, hospitals, or healthcare providers that are in-network. Out-of-network providers may trigger a fee.
• Coverage comparable to Medicare Parts A and B.
• You may need a primary care doctor and a referral to see a specialist.
• Out-of-pocket costs vary, though plans may cap how much you pay each year.
• Most plans include Medicare Part D coverage for drugs.

Comparing Medicare Costs

When comparing Original Medicare and Medicare Advantage plans, consider what’s covered and what you’ll pay.

Medicare Part A Costs

Most people don't pay a premium for Medicare Part A coverage.13 But both Parts A and B have deductibles and coinsurance. For Part A, here are 2024's costs for each benefit period:14

• Hospital inpatient deductible: $1,632 
• Hospital days 1–60: $0 coinsurance
• Days 61–90: $408 coinsurance per day
• Days 91 and beyond: $816 coinsurance per “lifetime reserve day” (up to 60 days over lifetime)
• Beyond lifetime reserve days: patient pays all costs

Note

Cost for 2025 will be available in October 2024.

Medicare Part B Costs

The standard monthly premium for Medicare Part B is $174.70 for 2024, though your premium may be higher based on income.14

The annual Medicare Part B deductible in 2024 is $240.14 After your deductible is met, you typically pay 20% of the Medicare-approved cost for most services, including doctor visits, outpatient therapy, and durable medical equipment.15

Medicare Advantage Costs

Medicare Advantage (Medicare Part C) costs depend on the plan you choose.16 Medicare Advantage members remain responsible for paying their Medicare Part B premiums. Some plans pay some or all of those on members' behalf, a practice known in the industry as a Medicare giveback benefit.

Some Medicare Advantage plans charge an additional monthly premium, but most don't. The amounts you pay for deductibles, copayments, and coinsurance can also vary.17

Medicare Part D Costs

The price of Medicare Part D drug coverage depends on the plan and your income. But here are generally the pieces you may pay for:5181920

• Premium: Medicare recipients can in a standalone Part D plan. For 2024, the average premium for those plans was projected to be $55.50.21
• Premium monthly adjustment amount: Higher-income Medicare recipients (making at least $103,000 if they're an individual tax filer or $206,000 for married filing jointly) pay a monthly adjustment of $69.90 to $419.30 in 2024.14
  
• Yearly deductible: In 2024, your annual deductible can't be more than $545.
• Copayment or coinsurance: Varies by plan and drug.
• Out-of-pocket spending limits: Once your out-of-pocket spending reaches $8,000 in 2024, you don't pay covered Part D drug copayments or coinsurance for the rest of the calendar year.21

The Inflation Reduction Act (IRA) has brought changes to Medicare. As of 2024, Part D plans cannot make you meet your deductible before it covers any adult vaccine or insulin product covered by Part D. In general, Part D plans can't charge more than $35 for a month's covered insulin product supply. Part D plans also can't charge you a copay or coinsurance for vaccines.21

In 2025, IRA changes include a 75% reduction in out-of-pocket spending, from $8,000 in 2024 to $2,000. However, the annual deductible will increase from $545 to $590.22

Original Medicare and Medicare Advantage plans generally don’t cover your emergency medical expenses outside the United States. However, you may be able to get Medigap or supplemental coverage if you plan to travel or live abroad.2324

How to Choose a Medicare Advantage Plan

Medicare offers a plan finder tool to help you compare Part C plans. But in general, Medicare Advantage plans can be structured as:4

• Health maintenance organization (HMO)
• Preferred provider organization (PPO)
• Private fee-for-service (PFFS)
• Special needs plans (SNPs)

Less common types of Medicare Advantage plans include HMO point-of-service plans and Medicare Medical Savings Account (MSA) plans.

When shopping for a Medicare Advantage plan, consider whether you'll be able to see out-of-network providers, whether a referral is required to see a specialist, and how much you’ll pay in premiums and out-of-pocket costs.

If You Miss Medicare Open Enrollment

If you miss the Medicare open enrollment period, you generally can’t change your coverage until the next one rolls around. There are, however, some exceptions. Special Enrollment Periods (SEPs) allow you to change your Medicare plan outside the open enrollment period.

You can learn more about special enrollment periods on the Medicare website, but you may qualify if any of the following apply to you.

You Relocate or Move to a New Facility

You could qualify to enroll in a new Medicare Advantage Plan or Medicare drug plan if you move to a new home that isn’t in your current plan’s service area. You could also qualify if you move back to the U.S. after living outside the country.

If you move into or out of a skilled nursing care facility or are released from prison, you may also qualify for a SEP.

You Lose Other Health Care Coverage

If you lose employer or COBRA (Consolidated Omnibus Budget Reconciliation Act) coverage, you'll likely be able to enroll in Medicare.

You could also qualify if you drop coverage under the Program of All-Inclusive Care for the Elderly (PACE), are no longer eligible for Medicaid, or are enrolled in a Medicare Advantage plan or Part D plan that isn’t renewed.

You Qualify for Related Programs

You could qualify if you're now eligible for both Medicaid and Medicare, or if you qualify for the Extra Help program to pay for Medicare Part D prescription drug coverage.

You Get the Option to Enroll in a Private Health Plan

If you have the option to join a private health plan through a new employer or union, you may qualify for a SEP to drop your current Medicare Advantage Plan or Medicare drug plan.

Frequently Asked Questions (FAQs)

What is Medicare Open Enrollment?

Medicare open enrollment is an annual period during which Medicare participants can make changes in coverage. Medicare open enrollment begins Oct. 15 and runs through Dec. 7 each year.11

Is There a Grace Period for Medicare Open Enrollment?

Generally, no. If you miss the open enrollment period, you’ll usually have to wait until next year's enrollment period to make Medicare coverage changes. However, you may be able to update your coverage at other times of the year if you qualify for a Special Enrollment Period.25

When Can I Enroll in Medicare?

You can enroll in Medicare for the first time in the year when you turn 65 or at a younger age for people with certain illnesses and disabilities. The Medicare initial enrollment period begins three months before your 65th birthday and lasts 3 months after your birthday month.12

The Bottom Line

During the Medicare open enrollment period, you can change your current Medicare coverage under parts A or B. Open enrollment runs from Oct. 15 to Dec. 7. A separate Medicare open enrollment period of Jan. 1 to March 31 applies to Medicare Advantage plans. If you miss your open enrollment period, you’ll generally have to wait until the following year to make changes, although there are some exceptions.

Article Sources

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1. Centers for Medicare & Medicaid Services. "CMS Fast Facts". Page 1.
2. Medicare.gov. “What Part A Covers.”
3. Medicare.gov. “What Part B Covers.”
4. Medicare.gov. “Understanding Medicare Advantage Plans.” Pages 12-15.
5. CMS.gov. "Medicare Advantage and Medicare Prescription Drug Programs to Remain Stable in 2024."
6. Medicare.gov. “How to Get Prescription Drug Coverage.”
7. Medicare.gov. “What’s Medicare Supplement Insurance (Medigap)?”
8. California Department of Insurance. “Long Term Care Insurance.”
9. Medicare.gov. “Nursing Home Care.”
10. Medicare.gov. "Joining a Plan".
11. Medicare.gov. "Joining a Health or Drug Plan."
12. Medicare.gov. "When Does Medicare Coverage Start?"
13. Medicare.gov. "Costs".
14. CMS.gov. “2024 Medicare Parts A & B Premiums and Deductibles.”
15. Medicare.gov. "Costs".
16. Medicare.gov. "What Does Medicare Cost?"
17. Medicare.gov. "Understanding Medicare Advantage Plans". Pages 6-7.
18. Medicare.gov. "Yearly Deductible for Drug Plans."
19. Medicare.gov. "Monthly Premium for Drug Plans."
20. Medicare.gov. "Catastrophic Coverage."
21. CMS.gov. "CMS Releases 2024 Projected Medicare Part D Premium and Bid Information."
22. CMS.gov. "Final CY 2025 Part D Redesign Program Instructions
    Fact Sheet." Page 4.
23. Medicare.gov. "Learn what Medigap Covers".
24. Medicare.gov. "Understanding Medicare Advantage Plans". Page 4.
25. Medicare.gov. “Joining a Plan.”