Edit note: Worth noting that CMS director Chris Klomp stated the agency is also considering ACO/Medicare Shared Savings Program models — not only private MA plans — as potential auto-enrollment defaults? The author’s framing focuses exclusively on the MA track, which is the more consequential and controversial option, but you may wish to add a brief parenthetical acknowledging the ACO alternative to pre-empt criticism of selective framing.

Today, new beneficiaries who do not make an active plan selection are enrolled in traditional, government-run Medicare — the default that has anchored the program since its inception. Under this proposed change, those seniors would be automatically funneled into private MA plans chosen by algorithms. CMS has not released details of its plan, but legislation introduced in the House would automatically assign new beneficiaries to the lowest-premium MA plan in their ZIP code and lock them in for three years. Assigning new enrollees to the plans with the narrowest networks and highest prior authorization rates prioritizes insurer profits over patient access, leaving vulnerable seniors saddled with inferior coverage.

The proposal’s architects are counting on a behavior pattern well documented for decades: Most people accept whatever default they’re assigned, whether it’s retirement savings, organ donation, or insurance selection. In Medicare, when low-income beneficiaries are automatically placed in Part D drug plans, only 16% opt out. Applied to MA, roughly 84% of defaulted enrollees would stay put — not because they chose to, but because doing nothing is easier than navigating the complexity of finding and choosing the right plan.

CMS Administrator Mehmet Oz, M.D., who has publicly advocated for MA for all since at least 2020, certainly knows this. The “stickiness” of default enrollment is not a side effect — it is the reason for the policy.

The sticky factor is exacerbated by federal law, which guarantees access to supplemental Medigap insurance only during a brief initial enrollment window. Beneficiaries who decide that the narrow networks and prior authorization requirements in MA aren’t meeting their needs will find that after 12 months, insurers can deny them Medigap coverage or charge prohibitive premiums based on pre-existing conditions. Without Medigap, there is no limit to out-of-pocket costs in traditional Medicare, exposing enrollees to possible financial ruin and making a switch out of MA impossible for most beneficiaries.

Without Congress adding an out-of-pocket cap to traditional Medicare or guaranteeing Medigap access regardless of health status, MA auto-enrollment isn’t a policy nudge — it’s a trap.

Proponents argue that MA delivers better value than traditional Medicare, but the evidence suggests otherwise. While enrollees in both programs report similar levels of satisfaction with care, the nonpartisan congressional advisory body known as MedPAC has consistently found that Medicare overpays private MA plans relative to what it would cost to cover the same enrollees in traditional Medicare — $76 billion in 2026 alone. Auto-enrollment would inflate that number significantly, threatening the long-term sustainability of Medicare while providing a financial windfall for private insurers.

Theoretically, the Center for Medicare and Medicaid Innovation could test MA auto-enrollment through a demonstration model, but only if it did not increase spending — a difficult bar to clear given that MA enrollees currently cost CMS roughly 14% more than comparable traditional Medicare enrollees. Changing the default enrollment pathway would otherwise require an act of Congress. But Project 2025 explicitly endorsed the concept, House legislation has already been introduced, and CMS leadership is now floating this idea publicly. The policy community cannot afford to treat this as a fringe proposal.

The question policymakers should be asking is not how to make MA the default, but how to make Medicare work better for all beneficiaries — for instance, by addressing overpayments to private plans, adding an out-of-pocket limit to traditional Medicare, and giving beneficiaries the tools to make informed decisions. Defaulting millions of seniors into private plans without their consent is not modernization. It is privatization by inertia. The idea must be rejected.

The opinions expressed in Fortune.com commentary pieces are solely the views of their authors and do not necessarily reflect the opinions and beliefs of Fortune.

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