US SB3848

Requires HHS to publish Medicare expenditure data on the CMS website in machine-readable files beginning in 2027, broken down by county and Metropolitan Statistical Area across 35 categories of beneficiaries based on enrollment status in Parts A, B, C, and D, supplemental coverage, and other health plans

Mandates publication of both historical data (10-year lookback) and projected expenditures (up to 5 years forward), with the 2027 report including retroactive enrollment data back to 2015

Requires MedPAC to include annual retrospective analysis comparing average expenditures for Medicare Advantage enrollees versus traditional fee-for-service beneficiaries, accounting for demographic differences and HCC risk scores but excluding favorable selection adjustments

Directs the Boards of Trustees of the Hospital Insurance and Supplementary Medical Insurance Trust Funds to report aggregate and average expenditures disaggregated by beneficiary categories in their annual reports starting in 2027

Requires MedPAC to publicly release all data and methodology used in their analysis at least 60 days before submission, allow 30 days for public comment, and respond to comments received