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Open Enrollment for 2024 Coverage through Medicare & the Marketplace—Basics for Advocates

October 19, 2023

Open Enrollment Periods (OEPs) are certain times of year when individuals can change their health care coverage. This fact sheet provides basic information on the annual OEPs in Medicare ( and the Marketplace ( and state-based exchanges) for the 2024 plan year and highlights issues that are of particular relevance to assisting low-income older adults. 

Note: This year is a busy time for health care enrollment changes, as states have restarted regular review of Medicaid eligibility after the end of the declared COVID-19 public health emergency. People age 65 and older who lose Medicaid coverage have access to a 6-month Special Enrollment Period to sign up for Medicare, so it is important to act quickly to avoid late enrollment penalties. A Special Enrollment Period to sign up for Marketplace coverage is also available for people who lose Medicaid and are not eligible for Medicare. 

Medicare Open Enrollment

Medicare enrollees have the opportunity to change their current health and prescription drug coverage during the Medicare OEP beginning October 15. It’s particularly important for Part C and Part D enrollees to review their coverage options each year as Medicare Advantage (MA) and Prescription Drug Plans (PDP) can change their cost-sharing, provider networks, and drug formularies.   


Individuals currently enrolled in Medicare Parts A or B (original Medicare), Part C (Medicare Advantage), and Part D (prescription drug coverage) should review their coverage to make sure they choose the most affordable options to meet their needs in 2024.    


October 15 to December 7, 2023.     


Medicare enrollees can change Medicare Advantage and Part D Prescription Drug Plans, or switch between Medicare Advantage and original Medicare. Any changes to coverage take effect January 1, 2024.  


Encourage your clients to make an appointment with a State Health Insurance Program (SHIP) counselor ( for free assistance. Coverage changes can be made at or   1-800-MEDICARE.   

Note: The Centers for Medicare and Medicaid (CMS) offers an online tool called the “Medicare Plan Finder” ( for comparing Medicare Advantage and Part D Prescription Drug Plan options. SHIP counselors have been trained on plans in the local area as well as changes to the plan finder tool. They are aware of issues with how information is presented that may be confusing and are in the best position to ensure enrollees are making informed choices.  

Note: Medicare Advantage Plans are continuing to offer new types of supplemental benefits that were first authorized for the 2020 plan year. It is important to understand that these new supplemental benefits are not available to all enrollees, have specific eligibility criteria and limitations, and may overlap with benefits covered by Medicaid for people dually eligible. Plans are required to provide specific information in their plan Member Handbook about the scope of a particular benefit and the requirements for accessing the benefit.  

Tips for Making Sure Your Clients Are Not Overpaying for Medicare Coverage 

When clients are reviewing their coverage and enrollment options, it also is an opportunity to make sure that they are enrolled in all programs for which they qualify. Despite being eligible, many people are not enrolled in the Part D Low Income Subsidy (LIS or “Extra Help”) program, which reduces prescription drug costs, or the Qualified Medicare Beneficiary (QMB) program, which pays for premiums and cost-sharing including both Part B premiums and also Part A premiums for people without free Part A. And starting in 2024, LIS is going to become more generous for certain individuals due to the Inflation Reduction Act’s prescription drug reforms. Helping clients get enrolled in these programs can save them thousands of dollars per year and enable them to access care they might otherwise forgo due to cost. 

In 2019, one million Medicare enrollees with the LIS paid an average of nearly $24/month for Part D premiums because they were not enrolled in a premium-free plan (a.k.a. a “benchmark” plan). Open Enrollment is the best opportunity for these individuals to review their coverage and change plans if necessary to better meet their needs and save money. Here are tips on how to help your LIS clients avoid overpaying for their coverage:  

  • Familiarize yourself with the tan “Choosers” notice sent to LIS enrollees so you can help your clients understand their options. 
  • Ask all your LIS clients whether they are paying a Part D premium. If they are or don’t know, urge them to review their options with a SHIP Counselor.
  • Remember that LIS enrollees can change plans once every quarter. If at any time during the year, you learn that an LIS client is paying Part D premiums, urge that client to review all plan options and consider changing plans.

Tips for Changing Medicare Coverage During Other Times 

Sometimes, individuals can change their Medicare Advantage or Part D Prescription Drug Plan outside of the annual OEP. For example, if a person has recently lost Medicaid coverage, moved, or experienced changes in the plan options available to them, they could be eligible for a Special Enrollment Period designed to help individuals change plans or move from Medicare Advantage to Original Medicare. Individuals dually enrolled in Medicare and Medicaid, individuals enrolled in LIS, and individuals living in nursing homes also have opportunities to change their Medicare coverage outside of the OEP.  Medicare Advantage enrollees can also change plans or switch to Original Medicare between January 1 and March 31st during the Medicare Advantage Open Enrollment Period.

Health Insurance Marketplace Open Enrollment

Older adults who are not eligible for Medicare and do not have other health insurance can use the annual fall OEP to enroll in or change 2024 coverage through the Affordable Care Act’s Health Insurance Marketplaces. Marketplace coverage also is an option for many older immigrants who are eligible for Medicare coverage but, because they do not have sufficient work history, must pay a premium for Part A. See the resources below for more information on what older immigrants need to know about eligibility for Medicare, Medicaid, and the Marketplaces.  

Individuals can enroll in Marketplace coverage through For 2024 enrollment, 19 states are operating their own state-based exchanges: California, Colorado, Connecticut, District of Columbia, Idaho, Kentucky, Maine, Maryland, Massachusetts, Minnesota, Nevada, New Jersey, New Mexico, New York, Pennsylvania, Rhode Island, Vermont, Virginia, and Washington. Links to each state’s marketplace website are also available on  


Consumers who are not eligible for Medicare and do not have other health insurance coverage can enroll or change coverage during open enrollment. Those who are eligible for Medicare but must pay a premium for Part A coverage also have the option to enroll in a Marketplace plan but will pay penalties if they later decide to switch to Medicare. See Medicare and the Marketplace.

Note: Consumers should enroll in Medicare as soon as they are eligible to avoid incurring late penalties. Enrolling in Marketplace coverage does not postpone an individual’s Medicare initial enrollment period and could expose the individual to late enrollment penalties as well as liability for any tax credits received for Marketplace coverage. 


This year, the Marketplace Open Enrollment period is November 1 to January 15, 2024. Consumers who want their plan to start on January 1, 2024 must sign up by December 15, 2023.  

Note: Some state-based Marketplaces have longer open enrollment periods and applications for Medicaid, and Marketplace financial assistance can be submitted year-round. Any changes in income or household size for current enrollees should be reported as soon as they occur.


Consumers can enroll in or change health and dental plans available in their state for the 2024 plan year. Applicants can also choose to be screened for premium tax credit and cost-sharing reduction eligibility as well as Medicaid eligibility.  


Consumers can visit or call 1-800-318-2596 to apply, change plans, or find free in-person assistance.  

Note: SHIPs, 1-800-Medicare and the Marketplace provide free interpreter services for individuals with limited English proficiency (LEP). Advocates should encourage their clients to ask for language assistance so that they can better understand their choices and get all their questions answered. Advocates should also remind clients that throughout the year, they can ask their plans for free interpreter assistance when they do not understand a plan communication or if they need other assistance.

Tips for Changing Marketplace Coverage During other Times

Sometimes, individuals can change their Marketplace coverage outside of the OEP. For example, if an individual has recently lost Medicaid, or experienced a life change like moving, marriage, or death of a household member, they may be eligible for a Special Enrollment Period. Learn more at


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