America’s seniors are quietly absorbing the cost of a structural flaw baked into Medicare’s financing rules. A report released Tuesday by the bipartisan Senate Joint Economic Committee found that overpayments to private Medicare Advantage insurers inflated Part B premiums by $13.4 billion in 2025 alone, a burden borne almost entirely by beneficiaries themselves, regardless of which type of Medicare plan they’re enrolled in.
The numbers are striking in their scope. According to the committee, the average Part B enrollee paid roughly $212 more last year than they would have under a payment-aligned system, while high-income beneficiaries subject to income-related surcharges faced additional costs of up to $682 annually. For the tens of millions of seniors who have their premiums automatically deducted from Social Security checks, that translates directly into a smaller monthly deposit, a quiet but compounding financial squeeze.
A Systemic Problem Built Into the Rules
The mechanism driving these costs is straightforward, if largely invisible to the public. By law, the standard Part B premium is set each year to cover 25 percent of expected Part B spending. That means any increase in overall program costs is automatically passed through to enrollees as higher monthly premiums, no matter whether those costs originated in traditional Medicare or in privately administered Advantage plans.
The Joint Economic Committee estimates that Medicare Advantage plans were paid an average of 120 percent of what it would have cost to cover the same beneficiaries under traditional Medicare in 2025, a gap MedPAC puts at roughly $84 billion. Because those elevated payments feed directly into the Part B spending baseline, every enrollee, including the 44 percent still in traditional Medicare, ends up subsidizing the difference. As JEC Chair David Schweikert put it: “When Medicare Advantage is overpaid, that money doesn’t just disappear, it shows up in the Medicare Part B premiums seniors pay every month.”
The Decade Ahead Looks Considerably Worse
The committee’s projections for the coming decade are sobering. Per-person Part B expenditures are expected to nearly double, climbing from around $9,100 in 2025 to over $18,000 by 2035. Because premiums are mechanically tied to those costs, annual baseline premiums are forecast to rise from approximately $2,200 today to around $4,500 by 2035. If Medicare Advantage overpayments continue at their current rate, the committee estimates they will account for roughly $450 of that figure, an avoidable burden, the report argues, that amounts to $2,600 per beneficiary over the decade.
The geographic distribution of that burden is uneven. According to the report, states with low Medicare Advantage enrollment, Wyoming, for instance, where only 21 percent of Medicare beneficiaries are in Advantage plans, see their traditional Medicare enrollees bearing a disproportionate share. Wyoming’s traditional Medicare beneficiaries effectively pay around $770 in excess premiums for every single Advantage enrollee in the state.
The report’s proposed remedy is direct: align Medicare Advantage payments with traditional Medicare costs. Whether Congress moves on that recommendation is another matter. The insurance industry has already pushed back, with AHIP calling the committee’s methodology “fundamentally flawed,” and Medicare administrator Mehmet Oz recently suggested the overpayment problem may be overstated. For now, the bill falls to seniors.
