This bill would change how much many Medicare Part D enrollees pay at the pharmacy. Instead of calculating your coinsurance from a drug’s full “list” price, plans would have to use the lower “net” price—the price after negotiated discounts and rebates—when that net price is lower. This applies for drugs on the plan’s formulary that use coinsurance (not a flat copay) and for costs above the yearly deductible and below the out-of-pocket limit, starting January 1, 2026 . The law defines “net price” as the plan’s negotiated price minus manufacturer price concessions reported for the prior year, which should better reflect the real price paid in the market . Some special categories of drugs are excluded by existing rules .

• Who is affected: People with Medicare Part D who pay coinsurance for certain drugs on their plan’s formulary .
• What changes: Coinsurance is based on the net (discounted) price, not the higher list price, which can lower what you pay at the counter .
• When: For plan years beginning on or after January 1, 2026 .