Medicare Advantage 2025 Enrollment Trends
Navigating Medicare Advantage: A Deep Dive into Enrollment Trends and Methodological Shifts
Understanding the landscape of Medicare advantage (MA) enrollment is crucial for beneficiaries, policymakers, and industry stakeholders. The Kaiser Family Foundation (KFF) provides valuable insights into these trends, but their methodology has evolved over time, impacting how we interpret the data. This article delves into KFF’s approach, highlighting key changes and their implications for understanding MA’s growing prevalence.
Data Sources and Early Trends:
KFF’s analysis primarily draws from the Centers for Medicare & Medicaid Services (CMS) Medicare Advantage Enrollment, Benefit and Landscape files. For recent enrollment figures, KFF utilizes the Medicare Enrollment Dashboard for March 2024 and March 2025. For earlier years, the CMS Chronic Conditions Data Warehouse Master Beneficiary Summary file (MBSF) for March is the source. The trend analysis begins in 2007, marking the earliest year with data based on March enrollment.
It’s important to note a data limitation: enrollment data is only provided for plan-county combinations with at least 11 beneficiaries. This means approximately 400,000 individuals residing in counties with lower county-wide plan enrollment are excluded from the analysis.
defining Eligibility: A Crucial Methodological Shift
A significant methodological change occurred in 2022, impacting how KFF calculates the share of eligible Medicare beneficiaries enrolled in MA.Previously, KFF included all Medicare beneficiaries with Part A and/or Part B coverage.However,the current approach focuses on beneficiaries who have both Part A and Part B coverage,as these are the individuals generally eligible for MA plans.
This shift is critical because the number of beneficiaries with only Part A or only Part B is substantial. In 2025, for instance, 5.8 million beneficiaries had only Part A or Part B, and are typically not eligible for MA. The divergence between these two calculation methods has become more pronounced over time. In 2010, the difference was minimal (24% of all enrollees vs. 25% with Parts A and B). By 2024, this gap widened substantially, with 49% of all Medicare beneficiaries enrolled in MA compared to 54% of those with both Parts A and B. These methodological adjustments are reflected in all data displayed by KFF, extending back to 2007.
Refining the Definition of “Medicare Advantage”: Exclusions and Consistency
In prior years, KFF’s definition of “Medicare Advantage” encompassed a broader range of private plans, including cost plans, Programs of All-Inclusive Care for the Elderly (PACE) plans, and Health Care Prepayment Plans (HCPPs), in addition to MA plans. However, starting with the 2022 analysis, these other plan types, along with Medicare Managed Plans (MMPs), are now excluded.
this exclusion is driven by the fact that these plans may have different enrollment requirements (e.g., availability to beneficiaries with only Part B) and payment structures compared to customary MA plans. By standardizing the definition to focus solely on MA plans, KFF aims to provide a more consistent and comparable analysis of MA enrollment trends. These exclusions are also applied to data from 2007 onwards.
Identifying Plan Sponsors: A New Reliance on Parent Institution Data
Beginning with the analysis of 2025 MA enrollment,KFF now relies on the “parent organization” field reported to CMS to identify plans sponsored by the same insurer.Previously, KFF supplemented this data with publicly available information on acquisitions, mergers, and business relationships. This shift in methodology may lead to a different number of total plan sponsors compared to previous analyses, as the new approach directly uses CMS-reported data.
Future Projections and data Comparisons:
For projections extending from 2026 to 2033, KFF utilizes the June Congressional Budget Office (CBO) Medicare Baseline for 2024. The CBO baseline for Medicare enrollment is based on individuals enrolled in part B, which generally includes those eligible for MA. However, it may also include some individuals with part B only who are not eligible for MA.
It is important for readers to be aware that enrollment counts published by other firms operating in the MA market,such as in company financial statements,may differ from KFF’s estimates. These discrepancies can arise from the inclusion or exclusion of specific plan types, such as Special Needs Plans (SNPs) or employer group health plans, in their respective analyses.
By understanding these methodological nuances, stakeholders can more accurately interpret KFF’s valuable data and gain a clearer picture of the evolving Medicare Advantage landscape.