Medicare Advantage (MA) overpayments are driving up Part B premiums for *all Medicare beneficiaries — including those who remain in Traditional Medicare (TM) and receive none of MA’s supplemental benefits. The Joint Economic Committee estimates this cost enrollees an extra $13.4 billion in 2025, with cumulative excess premiums of **$82 billion since 2016**.
How the Mechanism Works
By law, the standard Part B premium covers roughly 25% of expected Part B spending per aged enrollee. Because MA plans are paid an estimated 120% of what it would cost to cover the same beneficiaries under TM (per the Medicare Payment Advisory Commission), MA overpayments flow directly into higher Part B expenditures — and therefore higher premiums for everyone. The premium does not distinguish between MA and TM enrollees, so TM beneficiaries subsidize the higher MA spending without receiving MA benefits.
The math is straightforward: $84 billion in MA overpayments × 60.6% attributable to Part B × 26.4% financed by premiums = **$13.4 billion** in excess premiums, or roughly **$212 per enrollee** in 2025.
Who Bears the Burden
Approximately 84.9% of the excess premium burden falls on individuals — most commonly as a direct reduction in take-home Social Security benefits, since about 70% of Part B enrollees have premiums withheld from their Social Security checks. Federal taxpayers absorb 9.1% and state taxpayers 6.0%, primarily through Medicaid premium subsidies for low-income enrollees.
TM beneficiaries bore roughly $6 billion of the $13.4 billion total in 2025. The geographic impact is uneven: states with low MA enrollment (e.g., Wyoming at 21% MA penetration) see TM beneficiaries paying as much as $770 in excess premiums per MA enrollee in the state, while high-MA states like Minnesota (65% MA penetration) see only $114 — a nearly 7:1 disparity.
The Outlook and Policy Implications
Per-person Part B expenditures are projected to nearly double by 2035, from approximately $9,100 to over $18,000. All contributing factors — Part B’s share of total Medicare spending, the premium financing rate, and MA enrollment — are trending upward. If MA continues to be paid at 120% of TM, the per-beneficiary excess premium burden is projected to grow to roughly $450 per year by 2035.
The JEC brief concludes that aligning MA payment levels with TM would directly curb this avoidable premium growth. Gradual reform achieving payment parity could save each senior an estimated $2,600 over the next decade, while protecting net Social Security benefits for 50 million Part B beneficiaries.