This bill adjusts how Medicare Part B premiums are calculated for higher-income beneficiaries starting in 2027. Currently, Medicare applies an income-related surcharge to monthly premiums for people with modified adjusted gross incomes above $85,000, but this threshold has been frozen since 2018. The legislation extends this freeze through 2026 and then raises the income threshold to $171,000 beginning in 2027, while also creating new premium surcharge tiers for those earning between $171,000 and $500,000, and those earning $500,000 or more. The bill primarily affects higher-income Medicare beneficiaries who would otherwise pay higher premiums under current law, potentially reducing their out-of-pocket costs. The legislation takes effect in 2027 with no additional federal funding specified, as it adjusts existing premium structures rather than appropriating new money.