Medicare Advantage Enrollment Since The ACA: What The Projections Did Not Foresee

After the Affordable Care Act reduced payments to Medicare Advantage (MA) plans, economists and actuaries projected steep enrollment declines. Instead, MA enrollment more than doubled between 2010 and 2024, now covering more than half of Medicare beneficiaries. This Perspective examines the drivers behind this unexpected growth, including payment incentives for MA plans. Expanded business opportunities for brokers and marketing organizations, resulting from the entry of the baby-boom generation, and structural barriers to switching from MA to traditional Medicare have also contributed to MA enrollment growth. Although MA has broadened access to supplemental benefits, the program's rapid expansion raises questions about appropriate plan payments and the adequacy of beneficiary protections. To ensure that both MA and traditional Medicare serve beneficiaries effectively, reforms should focus on enhancing coverage information resources; improving plan oversight; realigning financial incentives; monitoring plan quality; and ensuring access to timely, affordable care.