Data Tool What We Know About Medicare Enrollment for Dual Enrollees
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The 12.5 million people enrolled in both Medicare and Medicaid as of 2020 are one of the country’s most vulnerable populations. Known as “dual enrollees,” these people tend to have worse health, including more chronic conditions that require more intensive and costly care than other Medicare enrollees. As of 2020, nearly all dual enrollees have incomes below $20,000 a year (87 percent), and they are disproportionately people of color (49 percent).

To qualify as a dual enrollee, a person must have a low income, limited resources, and be at least 65 years old or disabled. Medicare—a federal program—provides primary health insurance, while Medicaid—a joint federal and state program—assists with cost sharing and covers additional services, most notably nursing home care and other long-term services and supports. 

Dual enrollees have many options for their primary health insurance, including traditional Medicare, Medicare Advantage (MA), and specialized dual-eligible MA plans designed specifically for individuals with greater and specific health care needs. By understanding which plans dual enrollees have opted for over time, policymakers can better ensure a high-quality, cost-effective standard of care nationally and in their local communities.

Types of Medicare Available to Dual Enrollees

Fee-for-Service Medicare (FFS)

The traditional Medicare option, FFS means that the government pays providers directly for each inpatient and outpatient health care service received. Beneficiaries pay a monthly premium for all services, excluding inpatient hospital stays.

Medicare Advantage (MA) Plans

An alternative to traditional Medicare, these managed care plans are run by private companies. MA plans may offer—and beneficiaries can receive—supplemental services not covered under traditional Medicare but face different restrictions and cost structures. The Medicare Modernization Act of 2003 established three types of MA plans, called Special Needs Plans (SNPs): Chronic Condition SNPs, Institutional SNPs, and Dual SNPs.

Chronic Condition Special Needs Plan (C-SNP)

This is a specialized MA plan for individuals with severe or disabling chronic conditions.

Institutional Special Needs Plan (I-SNP)

This is a specialized MA plan designed for those who require a stay in a long-term care facility.

Dual Special Needs Plan (D-SNP)

By far the most common type of specialized MA plan for dual enrollees, this plan is designed to better meet and coordinate the needs of dual enrollees. State processes for integrating Medicare and Medicaid services into D-SNPs have varied.

Fully Integrated Dual Eligible Special Needs Plan (FIDE-SNP)

In 2011, the Affordable Care Act created FIDE-SNP, an additional class of D-SNP with more stringent integration requirements that fully integrates a dual enrollee’s care under a single care organization. A FIDE-SNP plan must contract with the state Medicaid agency and provide coverage for at least 180 days of nursing facility services, as well as other long-term services and supports.

Medicare-Medicaid Plans (MMP)

These plans are structured similarly to FIDE-SNP plans but are more focused on simplifying administrative processes, such as aligned enrollment processes. MMPs include a three-way contract between the Centers for Medicare and Medicaid Services (CMS), the state Medicaid agency, and the health plan. Ten states began operating MMPs under an agreement with CMS starting in 2013.

Program of All-Inclusive Care for the Elderly (PACE)

This community-based alternative plan is for a small number of people ages 65 and older who qualify for nursing home care. PACE plans deliver a full range of acute and long-term services in adult day centers.


Share of Dual Enrollees by Medicare Type between 2009 and 2021


Notes: FIDE-SNP = Fully Integrated Dual Eligible Special Needs Plan; D-SNP = Dual Special Needs Plan, excluding enrollees in FIDE-SNP; MA, non-specialized = Medicare Advantage plan, excluding specialized plans (D-SNP, FIDE-SNP, C-SNP, I-SNP); MMP = Medicare-Medicaid Plans. Data represent all US enrollees, excluding those who reside in US territories. There may be some administrative reporting errors. 


The type of Medicare that dual enrollees gravitate toward has changed significantly between 2009 and 2021, with further variation by age, eligibility type, and benefit level. Nationally, the share of dual enrollees in FFS Medicare has decreased during this timeframe, with D-SNP plans seeing the largest enrollment gains. These trends are less pronounced among dual enrollees with partial benefits who do not qualify for services where Medicaid is the primary payer, lessening the advantages of D-SNPs that coordinate or integrate with Medicaid. 


Notes: FFS = fee-for-service; SNP = Special Needs Plan; C-SNP= Chronic Condition Special Needs Plan; D-SNP = Dual Special Needs Plan; FIDE-SNP = Fully Integrated Dual Eligible Special Needs Plan; I-SNP = Institutional Special Needs Plan, MA, non-specialized = Medicare Advantage plan, excluding specialized plans; MMP = Medicare-Medicaid Plans; PACE = Program of All-Inclusive Care for the Elderly. Data represent all dual Medicare-Medicaid enrollees in the reported county as of December 2021 and the change in dual enrollees between January 2009 and December 2021. In some counties, Medicare enrollment by type is too small to report. In these cases, we “coarsen” the reported statistics by subtracting or adding a small number of enrollees across groups and using inequalities for others. In extreme cases, we entirely suppress values, reporting "N/A" instead.


About the Data

Data for this project come from the administrative Medicare Master Beneficiary Summary File and the corresponding Plan Characteristics File, spanning calendar years 2009 through 2021. These data are restricted, include the universe of all Medicare enrollees in a given calendar year, and are accessible only to approved researchers through a Research Identifiable File Data Use Agreement with CMS. The reported statistics in the maps and tables are based on enrollment totals by type of Medicare enrollment, calendar month, and county and adhere to the CMS cell size suppression policy. For readers interested in state-level enrollment statistics, which are not the focus of this project, click here.


This data tool was supported by Arnold Ventures. We are grateful to them and to all our funders, who make it possible for Urban to advance its mission. The views expressed are those of the authors and should not be attributed to the Urban Institute, its trustees, or its funders. Funders do not determine research findings or the insights and recommendations of our experts. More information on our funding principles is available here. Read our terms of service here.

RESEARCH Kyle J Caswell, Timothy Waidmann

DESIGN Christina Baird


EDITING Sarah LaCorte

WRITING Wesley Jenkins

Research Areas Health and health care
Tags Federal health care reform Health care delivery and payment Health care laws and regulations Health insurance Medicare Medicare and Medicaid dual eligibility Public health
Policy Centers Health Policy Center
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