MEDICARE FOR ALL WHO WANT IT An Actuarial and Economic Framework for a Voluntary Federal Public Option Institutional Design, Risk Allocation, and Fiscal Parameter Sensitivity

This paper designs and stress-tests Medicare for All Who Want It (M4AWWI), a voluntary federal public option pairing an income-subsidized base plan with a regulated private wraparound market, an employer-coverage firewall, ACA-consistent risk adjustment, and an all-payer catastrophic reinsurance pool open to public and private carriers on identical terms. Unlike the ACA, which relied exclusively on subsidized private plans and allowed its transitional reinsurance to expire, M4AWWI introduces a public competitor and institutionalizes catastrophic reinsurance permanently. Unlike Buttigieg's 2020 campaign concept—articulated as a slogan without architecture—this paper supplies the institutional design. Unlike single-payer Medicare for All, it retains private insurance and finances coverage through premiums and targeted subsidies rather than broad new taxes. Unlike rival public-option bills conceived as standalone products, M4AWWI adds the regulated supplement market, the symmetric catastrophic pool, and a political frame built for a rural and populist electorate. The method is institutional comparison, statutory-design analysis, and a three-case parameter sensitivity exercise—not a microsimulation, actuarial valuation, or CBO score. Under jointly bounding assumptions for average enrolment (12–28 million) and total plan cost ($650–$875 PMPM), the illustrative ten-year net federal subsidy ranges from approximately $0.23 trillion to $0.92 trillion before optional dedicated revenues. All figures are arithmetic illustrations, not forecasts. The paper concludes that the architecture is technically plausible but that solvency, provider-network adequacy, adverse-selection dynamics, distributional incidence, and federal–state interactions require independent microsimulation and legal analysis before enactment. The original contribution is the integrated architecture and the explicit allocation of catastrophic-tail risk across all payers on common terms.