How Medicare Part D Premiums Are Affected by IRMAA in 2026 Besides increasing Medicare Part B premiums, IRMAA brackets 2026 also impact Medicare Part D prescription drug plan costs. Higher-income beneficiaries pay additional surcharges on top of their standard Part D premiums, which vary based on the 2026 IRMAA brackets. These charges apply regardless of which Medicare Part D plan a ... https://www.federalpensionadvisors.com/post/2025-irmaa-brackets