Trends in the level and composition of supplemental benefits in Medicare Advantage.

Medicare Advantage (MA) plans that bid below benchmarks (or bidding targets) receive a portion of that difference as rebates, which they then must return to beneficiaries through supplemental benefits or reduced premiums or cost-sharing. Using Centers for Medicare & Medicaid Services data, we evaluate the growth in rebates and concomitant changes in supplemental benefit composition among health maintenance organizations (HMOs) and local preferred provider organizations (PPOs) from 2011 through 2022. Average rebates grew considerably, particularly after 2015 and among PPOs. Alongside this rebate growth, the share of enrollees in plans offering dental, vision, and hearing benefits also increased, with nearly universal coverage of these benefits among both HMOs and PPOs by 2022. Medicare Advantage plans also increasingly reduced beneficiary Part D premium obligations, while increasing beneficiary financial exposure in the form of higher Part D deductibles, medical out-of-pocket maximums, and cost-sharing for inpatient stays. These findings are particularly relevant as policymakers debate the merits of various reforms to MA payment policy.