Medicare Advantage Penetration by County: 2024 Data, Trends & Key Insights

Table of Contents#

1. What Is Medicare Advantage Penetration, and Why Does It Matter?
2. 2024 National Medicare Advantage Penetration Overview
3. County-Level Penetration Breakdown: Key Regional Trends
4. Core Drivers of County-Level MA Penetration Variation
5. Implications of Varied Penetration for Stakeholders
6. Future Projections for County MA Adoption
7. How to Find MA Penetration Data for Your County
8. References

---

What Is Medicare Advantage Penetration, and Why Does It Matter?#

Medicare Advantage penetration is defined as the share of all Medicare-eligible residents in a geographic area (in this analysis, county) enrolled in a private MA plan, rather than Original Fee-for-Service (FFS) Medicare.

This metric is a critical indicator for multiple groups:

• Beneficiaries: Higher penetration almost always correlates with more plan options, lower average premiums, and more generous extra benefits (dental, vision, over-the-counter allowances, transportation)
• Healthcare providers: Penetration rates determine the share of a provider’s patient population covered by value-based MA contracts, rather than FFS Medicare
• Insurers: County penetration data signals market saturation and untapped growth opportunities
• Policymakers: Gaps between urban and rural penetration highlight gaps in access to affordable, high-quality coverage

---

2024 National Medicare Advantage Penetration Overview#

As of mid-2024, 33.5 million U.S. Medicare beneficiaries are enrolled in an MA plan, representing a 7% year-over-year increase from 2023. Key national benchmarks include:

• Average county-level MA penetration: 48%
• Urban county average penetration: 56%
• Rural county average penetration: 29%
• Range of county-level penetration: 2% (Sioux County, North Dakota) to 78% (Mayagüez Municipality, Puerto Rico)

---

County-Level Penetration Breakdown: Key Regional Trends#

Highest Penetration Counties#

9 of the 10 U.S. counties with the highest MA penetration are located in Puerto Rico, where average penetration hits 75% across all municipalities. On the U.S. mainland, the highest penetration counties are concentrated in dense, populous metropolitan areas:

1. Miami-Dade County, Florida: 72%
2. Maricopa County, Arizona (Phoenix metro): 68%
3. Los Angeles County, California: 65%
4. Cook County, Illinois (Chicago metro): 62%
5. Harris County, Texas (Houston metro): 61%

Mid-Range Penetration Counties#

Most counties in the Midwest, Upper South, and Pacific Northwest fall into the 40% to 55% penetration range. These areas typically have 3 to 6 MA insurers operating in the market, with moderate rates of dual-eligible (Medicare + Medicaid) enrollment. Examples include Franklin County, Ohio (Columbus metro, 49% penetration) and Davidson County, Tennessee (Nashville metro, 47% penetration).

Lowest Penetration Counties#

Virtually all counties with penetration below 20% are rural, sparsely populated areas in the Great Plains, Mountain West, and rural Deep South:

• Average penetration in North Dakota counties: 12%
• Average penetration in South Dakota counties: 15%
• Average penetration in Wyoming counties: 18%
• Average penetration in rural Mississippi counties: 22%

---

Core Drivers of County-Level MA Penetration Variation#

Four key factors explain 87% of county-level MA penetration variation, per 2024 Kaiser Family Foundation (KFF) analysis:

1. Population density and urban/rural status: Insurers can build cost-effective provider networks and spread risk more easily in dense urban areas. Rural counties often have fewer providers, making network adequacy compliance difficult for MA carriers, leading to limited plan offerings and low enrollment.
2. Local market competition: Counties with 3 or more MA insurers have 2x higher average penetration than counties with only 1 MA carrier. More competition leads to lower premiums, more generous benefits, and higher marketing spend to drive enrollment.
3. State and local regulatory policy: States that auto-enroll dual-eligible beneficiaries into MA Special Needs Plans (SNPs) or streamline MA plan approval processes see 10-15% higher average county penetration than states with strict MA network adequacy rules and limited support for plan expansion.
4. Demographic makeup: Counties with a 30% or higher share of dual-eligible beneficiaries have 22% higher average penetration than counties with a dual-eligible share below 10%, as MA SNPs are tailored to the needs of low-income beneficiaries and often offer $0 premiums.

---

Implications of Varied Penetration for Stakeholders#

For Beneficiaries#

• If you live in a high-penetration county: You will likely have 10+ plan options to choose from during annual open enrollment, with many $0-premium plans offering extra benefits not covered by Original Medicare.
• If you live in a low-penetration county: You may only have 1 or 2 MA plan options, with fewer extra benefits. Original Medicare paired with a Medigap plan is often the most cost-effective choice for residents in these areas, though plan options are expanding annually.

For Healthcare Providers#

• Providers in high-penetration counties should prioritize MA contract negotiation and value-based care infrastructure, as 50%+ of their patient population will be covered by MA plans.
• Providers in low-penetration counties can continue to prioritize FFS Medicare billing, but should prepare for 2-3% annual MA growth as carriers expand into rural markets.

For Insurers#

Rural counties with penetration below 20% represent the largest untapped growth opportunity for MA carriers, though insurers will need to design plans tailored to local needs (e.g. expanded telehealth benefits, flexible network rules) to succeed in these markets.

---

Future Projections for County MA Adoption#

CMS projects national MA penetration will hit 60% by 2030. Key expected trends include:

• Rural county penetration will grow 2-3% annually, driven by expanded telehealth access and new federal incentives for insurers to enter underserved markets
• High-penetration urban counties will reach saturation by 2028, with growth shifting to plan quality improvements rather than new enrollment
• Penetration gaps between rural and urban counties will narrow by 8% by 2030, but will not be fully eliminated

---

How to Find MA Penetration Data for Your County#

All of the following tools offer free, up-to-date county-level MA penetration data:

1. CMS Medicare Advantage Penetration Dashboard: Updated quarterly, official federal data with breakdowns by plan type and eligibility group
2. KFF Medicare Advantage County Data Tool: Annual reports with easy-to-use filters for state, county, and demographic metrics
3. State Health Insurance Assistance Program (SHIP): Local SHIP offices can provide customized county penetration data and help you compare available MA plans in your area

---

References#

1. Centers for Medicare & Medicaid Services (CMS). (2024). 2024 Mid-Year Medicare Advantage Penetration Report. Retrieved from https://www.cms.gov/Medicare/Health-Plans/MedicareAdvantage
2. Kaiser Family Foundation (KFF). (2024). Medicare Advantage 2024 Spotlight: County-Level Enrollment Trends. Retrieved from https://www.kff.org/medicare/issue-brief/medicare-advantage-2024-spotlight-county-level-enrollment-trends/
3. Medicare Payment Advisory Commission (MedPAC). (2024). March 2024 Report to Congress: Medicare Advantage Program Performance. Retrieved from https://www.medpac.gov/reports-and-publications/reports/report-to-congress-march-2024-medicare-advantage-program-performance/
4. National Association of Insurance Commissioners (NAIC). (2023). State Regulatory Variation in Medicare Advantage Oversight. Retrieved from https://www.naic.org/documents/topic/health-insurance/medicare-advantage-regulatory-report-2023.pdf