On October 16, the Centers for Medicare and Medicaid Services (CMS) released the 2025 Part D formulary files. With the landscape files released in late September, these data indicate how the Part D market is shifting in the first year of full Part D benefit redesign implementation.

Drug Coverage

The average percentage of brand drugs covered is increasing from 2024 to 2025, with some differences between Prescription Drug Plans (PDPs) and Medicare Advantage Prescription Drug plans (MA-PDs). The average percentage of brand drugs covered on PDP formularies increased by two percentage points, from 31% of all brand drugs covered on formulary in 2024 to 33% in 2025. For MA-PDs the average percentage of brand drugs covered is increasing by three percentage points, from 35% in 2024 to 38% in 2023 (Figure 1).

Figure 1: Average Percentage of Brand Drugs Covered vs. Not Covered on PDP and MA-PD Formularies, 2024 and 2025

Similarly, the average percentage of all drugs (brands and generics) covered is increasing by two percentage points between 2024 and 2025 for both PDPs and MA-PDs. The share of all covered drugs is higher for MA-PDs (56% covered) compared to PDPs (52% covered) in 2025.

Cost Sharing and Utilization Management

Part D plans are increasing management of covered drugs through shifts in cost sharing and utilization management.

The number of coinsurance tiers is increasing substantially for both PDPs and MA-PDs. For 2025, the share of PDPs with three coinsurance tiers is increasing by 26 percentage points. The share of MA-PDs with two or more coinsurance tiers is increasing by 3.5 times, or by 45 percentage points from 2024 to 2025 (Figure 2).

Figure 2: Percentage of PDPs and MA-PDs by Number of Coinsurance Tiers, 2024 and 2025

The average percentage of all drugs on coinsurance tiers is increasing from 30% in 2024 to 50% in 2025 for MA-PDs and from 69% to 76% for PDPs.

Use of prior authorization for covered brand drugs is also increasing by two percentage points for PDPs and by three percentage points for MA-PDs. Rates of prior authorization remain slightly higher for PDPs than MA-PDs (Figure 3).

Figure 3. Average Percentage of Brand Covered Drugs by Utilization Management Tool Among PDPs and MA-PDs, 2024 and 2025

Other Potential Shifts by Therapeutic Area and Region

Previous Avalere research has found even greater shifts in coverage, cost sharing, and utilization management within specific products, therapeutic areas, and regions. Changes for some therapeutic areas may be more extreme than others, particularly as plans continue to implement changes under the Inflation Reduction Act. As maximum fair prices of the first 10 selected drugs for negotiation to take effect in 2026, Part D plans may have already began to shift formulary management strategies for these products and their competitors.

With fewer Part D plan options available in 2025, differences in formulary changes across therapeutic areas, plan types, and regions may cause more disruption for patients in 2025.

To learn more about the impacts of Part D market changes, connect with us.

Methodology

Avalere used the 2024 and 2025 Part D formulary files released by CMS. Part D covered drugs are defined as those that appear on at least 1 Part D formulary. Results presented are weighted based on enrollment, and excludes territories, Employer-Group Waiver Plans, Special Needs Plans, Cost plans, Medicare-Medicaid Plans, and Program of All-Inclusive Care for the Elderly plans.