Medicare Affordability Update
Excess Part B premiums
7th in the U.S.
Total burden on individuals
5th in the U.S.
Excess TM premiums
6th in the U.S.
State fiscal burden
11th in the U.S.
Federal fiscal burden
11th in the U.S.
Total public sector fiscal burden
11th in the U.S.
About this data update
This monthly update reports the Joint Economic Committee’s latest estimates of excess Part B premiums attributable to Medicare Advantage (MA) overpayments for Illinois and its congressional districts.
By law, Medicare Part B premiums are set to finance 25 percent of projected Part B spending, with some paying additional premiums based on income. This financing design means that 25 percent of any increase in Part B spending is automatically passed through to enrollees as higher Part B premiums. These premiums apply equally to beneficiaries regardless of whether they enroll in Traditional Medicare or MA. Because payments to MA plans are financed through Part B, it costs more to cover enrollees in MA than to cover those in Traditional Medicare, which increases total Part B spending and mechanically raises Part B premiums for beneficiaries nationwide, including in Traditional Medicare.
While the premium increase applies uniformly, the resulting dollar burden varies across states, congressional districts, and individuals based on beneficiary income (income-related premiums, or IRMAA), the share of beneficiaries with publicly subsidized premiums, and local Medicare enrollment levels.
The Joint Economic Committee’s forthcoming issue brief documents this mechanism in detail and estimates that MA overpayments increased Part B premiums by over $13 billion nationally in 2025. This data update quantifies that burden for seniors in Illinois both for individuals through greater Social Security deductions and for the public collectively through higher state Medicaid expenditures, which are financed by state tax revenues.
Consequences of Medicare Advantage overpayments for Traditional Medicare beneficiaries
The effect of Medicare Advantage (MA) overpayments on Part B premiums is uniform whether a beneficiary enrolls in Traditional Medicare or MA. However, MA overpayments help finance more generous MA benefits that are not available in Traditional Medicare. This includes Part B premium “givebacks,” under which an MA plan pays some or all of the Part B premium on behalf of its enrollees.
As a result, redistribution flows from Traditional Medicare to MA. In Illinois, there are 11.0 Traditional Medicare beneficiaries bearing this higher premium burden for every 10 MA beneficiaries who ultimately receive the greater benefits. This means that 1.1 Traditional Medicare beneficiaries pay $232 in excess for each MA beneficiary in Illinois.
$249,326,946
Excess TM premiums
Excess Part
B premiums faced by Traditional Medicare enrollees despite not receiving
Medicare Advantage benefits
$232
Amount paid in excess by TM
beneficiaries for every MA beneficiary
Excess Part
B premiums faced by Traditional Medicare enrollees for each MA
beneficiary
11.0
Number
of TM beneficiaries for every 10 MA beneficiaries
Distribution across congressional districts in Illinois
Medicare enrollment, Medicare Advantage penetration, and income distributions vary across states and congressional districts, leading to substantial variation in the excess Part B premium burden.
Summary of methodology
To quantify the excess premium burden borne by constituents in each congressional district, we crosswalk local enrollment patterns from monthly CMS enrollment files at the county level to congressional districts using Census population weights. Our results reflect gross premium liability; for some MA enrollees, the net out-of-pocket effect may be lower when Part B premiums are fully or partially covered by the plan as a supplemental benefit.
In 2022, the U.S. Census Bureau adopted Connecticut’s nine new planning regions, which replaced its eight counties. As a result, the JEC was unable to include Connecticut in the district-level analysis. Therefore, the total number of districts included is 431, including DC’s at-large district and excluding Connecticut’s five districts.
Full methodology, assumptions, and national estimates are provided in the forthcoming JEC issue brief.
Congressional District 1
Rep. Jonathan L. Jackson (D)
293rd out of 431 districts, where 1st is highest
Congressional District 2
Rep. Robin L. Kelly (D)
287th out of 431 districts, where 1st is highest
Congressional District 3
Rep. Delia C. Ramirez (D)
393rd out of 431 districts, where 1st is highest
Congressional District 4
Rep. Jesus G. “Chuy” Garcia (D)
399th out of 431 districts, where 1st is highest
Congressional District 5
Rep. Mike Quigley (D)
358th out of 431 districts, where 1st is highest
Congressional District 6
Rep. Sean Casten (D)
176th out of 431 districts, where 1st is highest
Congressional District 7
Rep. Danny K. Davis (D)
411th out of 431 districts, where 1st is highest
Congressional District 8
Rep. Raja Krishnamoorthi (D)
337th out of 431 districts, where 1st is highest
Congressional District 9
Rep. Janice D. Schakowsky (D)
246th out of 431 districts, where 1st is highest
Congressional District 10
Rep. Bradley Scott Schneider (D)
250th out of 431 districts, where 1st is highest
Congressional District 11
Rep. Bill Foster (D)
295th out of 431 districts, where 1st is highest
Congressional District 12
Rep. Mike Bost (R)
134th out of 431 districts, where 1st is highest
Congressional District 13
Rep. Nikki Budzinski (D)
283rd out of 431 districts, where 1st is highest
Congressional District 14
Rep. Lauren Underwood (D)
370th out of 431 districts, where 1st is highest
Congressional District 15
Rep. Mary E. Miller (R)
62nd out of 431 districts, where 1st is highest
Congressional District 16
Rep. Darin LaHood (R)
109th out of 431 districts, where 1st is highest
Congressional District 17
Rep. Eric Sorensen (D)
231st out of 431 districts, where 1st is highest