Cost Sharing Trends Show Broad Shifts in the Part D Market

Below is an edited excerpt from a recent white paper authored by Manatt Health. Click to read the full paper.

The Inflation Reduction Act (IRA) fundamentally changed the economics of the Part D marketplace. In this white paper, Nate Pauly and Ross Margulies analyze Medicare Part D formulary and enrollment data to assess trends in cost sharing requirements and formulary placement during Medicare Part D redesign (2024-2025), in addition to examining trends among the 10 drugs selected for negotiation for 2026.

Early evidence suggests that plans have responded to increased costs driven by the IRA’s Part D benefit redesign provisions by increasing cost sharing requirements for Part D enrollees to recalibrate premiums and plan liabilities. Changes in coinsurance requirements among IPAY 2026 negotiated drugs likely reflect changes at the formulary tier-level associated with Part D redesign, rather than being driven by the drug price negotiations themselves.

Click to read the full paper.