Background 

During the annual Medicare Open Enrollment Period (October 15–December 7), beneficiaries may select coverage for the upcoming plan year by enrolling in either a standalone Prescription Drug Plan (PDP) to pair with Original (fee-for-service) Medicare or a Medicare Advantage Prescription Drug (MA-PD) plan, which combines medical and prescription drug coverage. Enrollment decisions made during this period take effect on January 1 of the following year (e.g., January 1, 2026, for the 2026 plan year).  

While many plans are available to all Medicare beneficiaries, some limit eligibility to specific populations. These include Special Needs Plans (SNPs), such as Chronic Condition Special Needs Plans (C-SNPs) for individuals with qualifying chronic conditions, Dual Eligible Special Needs Plans (D-SNPs) for individuals eligible for both Medicare and Medicaid, and Institutional Special Needs Plans (I-SNPs) for beneficiaries requiring institutional or long-term care. In addition, Employer Group Waiver Plans provide coverage to retirees affiliated with specific employers or unions. 

In mid-February, the Centers for Medicare and Medicaid Services (CMS) released the 2026 MA and Part D enrollment data. These data offer an early snapshot of beneficiary plan selections for the 2026 plan year and highlight shifts in enrollment between MA-PDs and standalone PDPs. 

PDP and MA-PD Enrollment Trends 

From 2025 to 2026, overall Part D enrollment increased from 55.4 million to 56.9 million (a 2.7% increase). Over this period, enrollment in PDPs grew by 7.2% while enrollment in MA-PDs decreased by 0.5% (Figures 1 and 2). This is a notable shift from trends in recent years. MA-PD enrollment had climbed from 26 million in 2022 to 31.8 million in 2025, with annual growth of 7.4% from 2023 to 2024 and 4.3% from 2024 to 2025. By contrast, PDP enrollment was stable at 23.4 million in 2022 and 23.5 million in 2025, before rising to 25.2 million in 2026.  

PDP enrollees are increasingly selecting lower premiums plans. In 2026, 64% of PDP enrollees chose plans with premiums under $25, up from 49% in 2025. At the same time, the share selecting plans with premiums of $100 or more increased to 17% in 2026, up from 12% in 2025.  

Figure 1: Part D Enrollment by Plan Type, 2022–2026, in Millions  

Note: Values may not sum due to rounding; includes SNPs; *Other categories include cost plans, Medicare-Medicaid Plans, and Program of All-Inclusive Care for the Elderly plans  ; Source: Avalere Health analysis using enrollment data released by the Centers for Medicare & Medicaid Services in March of each year, reflecting enrollment effective in February for 2022–2025. For 2026, February data was used to reflect January enrollment.

Figure 2: Annual Change in PDP and MA-PD Enrollment, 2023–2026 

Enrollment Changes in Largest Plan Sponsors  

In 2026, 69% of Part D enrollees were enrolled with one of the five largest Part D plan sponsors, down from 71% in 2025. Health Care Service Corporation had the largest increase in total Part D enrollment, increasing by 88% from 2025, likely driven in part by its acquisition of Cigna’s Medicare Part D business. Humana had the second largest increase in total Part D enrollment, growing by 22% in 2026. UnitedHealth experienced the largest decline in Part D enrollment, with enrollment falling by nearly 17% from 2025.  

Among the top eight MA parent organizations by enrollment, combined market share fell by three percentage points in 2026. Blue Cross Blue Shield of Michigan Mutual Ins. Co. experienced almost a 15% decline in MA enrollment while Humana had a 21% increase, highlighting the range of enrollment changes among leading MA parent organizations. 

Enrollment in C-SNPs and D-SNPs Increased while I-SNP Enrollment Decreased 

In 2026, 23% of all MA enrollees were enrolled in a SNP (Figure 4). Overall, SNP enrollment increased by 12% from 7.3 million in 2025 to 8.2 million in 2026. From 2025 to 2026, the number of available C-SNP and D-SNP plans increased by 24%, while enrollment in these plans grew by 12%. In contrast, I-SNP offerings and enrollment remained relatively stable and continued to represent a small share of the overall market. 

Figure 3: SNP Enrollment by C-SNP, D-SNP, and I-SNP, 2022-2026, in Millions

Note: Values may not sum due to rounding.; Source: The analysis was conducted using CMS’s enrollment and landscape file and Avalere’s proprietary database PlanScape®. The analysis uses enrollment data released by the Centers for Medicare & Medicaid Services in March of each year, reflecting enrollment effective in February for 2022–2025. For 2026, February data was used to reflect January enrollment.

Stakeholder Considerations 

Despite continued declines in the number of standalone PDPs offered in 2025 and 2026 relative to prior years, PDP enrollment has increased while MA-PD enrollment has largely leveled off. For plan sponsors, this divergence may signal changing beneficiary preferences around premium sensitivity, benefit offerings, pharmacy network design, and the value proposition of integrated MA coverage versus a standalone Part D product. 

Previous Avalere Health analysis of Part D claims data has found substantial difference in out-of-pocket costs and drug spending trends by plan type (PDP vs. MA-PD), reflecting variation in utilization management (UM), formulary design, and benefit structures.  As Inflation Reduction Act provisions drive further changes to Part D—including benefit redesign, evolving formulary strategies, and shifting liability across the benefit—stakeholders should reassess how PDP and MA-PD offerings compete on total cost, member affordability, and access. There are several stakeholder-specific considerations: 

• Plan Sponsors: Continue to assess PDP vs. MA-PD portfolio strategy, bid/premium positioning, formulary designs, and UM approaches under the new liability structure to understand how these choices affect retention, Star Ratings, and member experience. 

• Drug Manufacturers: Track shifts in enrollment mix, as differences in MA-PD vs. PDP formulary placement and UM can affect volume and net price; adjust contracting and market access strategy accordingly. 

• Providers: Prepare for changes in patient cost exposure that affect prescribing, adherence, and administrative burden (e.g., prior authorization), and adjust medication access workflows and financial counseling. 

To learn more about how MA and Part D enrollment shifts may impact your organization, connect with us. 

Methodology 

Avalere Health used MA and Part D enrollment data released in February 2026 by CMS to conduct this analysis. Enrollment files from March of each year were used to reflect enrollment effective as of February for the corresponding years. The analysis includes territories and employer plans.