The Part D Premium Protection Act of 2026 requires the Secretary of Health and Human Services to establish a temporary premium credit for individuals enrolled in Medicare Part D prescription drug plans during 2027. This credit is designed to reduce the out-of-pocket premium costs for beneficiaries for that year. The amount of the credit will be equivalent to the average premium reduction achieved through the Part D Premium Stabilization Demonstration, as calculated from premium rates between January 2025 and December 2026. The Secretary will notify plan sponsors of this credit amount, who will then apply it to enrollees' 2027 premiums, ensuring the charge is not less than zero. Subsequently, the Secretary will reimburse the appropriate plan sponsors for the total credit amounts applied to enrollees' premiums.