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Medicare Advantage Enrollment Tracker · Illinois

Medicare Advantage Enrollment in Illinois

Illinois had 1,098,001 Medicare Advantage members in September 2026, by the CMS county file, which includes employer group plans. That is up 1.9% from Sep 2025, close to the national 2.0%. Illinois ranks 10th by members and holds 3.1% of the national total.

Aetna/CVS leads with 31.7% of members who have a carrier label (contract file, September 2026). Among individual plans, which leave out employer group coverage, enrollment is up 2.7% in the 12 months to September 2026.

By Senior Deal Club Standards Desk · Data as of September 2026 · Editorial policy

Data as ofCMS public files, monthly snapshot

  • These totals include employer and union group plans.
    Why this matters

    The CMS contract and county files count group plans that retirees get through a former employer. They are not plans you can pick on your own. Counts here are larger than the individual-plan counts on county pages.

  • Some months are missing from the source.
    Why this matters

    CMS did not publish every month. Lines break at a missing month instead of guessing a value. A dotted line, where shown, only joins the two sides.

Illinois at a glance

Medicare Advantage members

1,098,001

Illinois members by month: from 796K in Jan 2023 to 1.1M in Sep 2026

County file · Sep 2026. Includes employer group plans. Rank: 10.

County file · Sep 2026
CMS state, county and plan-type file (SCP). The same plans split by state and county, with employer and union group plans included. CMS hides counts of 10 or fewer.

12-month change

+1.9%

up 1.9 percent vs Sep 2025

County file · Sep 2026. National: +2.0%.

Share of national total

3.1%

County file · Sep 2026. Of jurisdictions that report every month.

Individual plan members

809,601

Individual MA · Sep 2026. Employer group plans left out.

Individual MA · Sep 2026
Individual Medicare Advantage plans (IND), from county data. Employer and union group plans are left out, so counts are smaller than in the other two files.

Largest carrier

Aetna/CVS

31.7% of members with a carrier label. Contract file · Sep 2026.

Illinois members by month

Medicare Advantage members in Illinois

Members, by month.

County file · Sep 2026
CMS state, county and plan-type file (SCP). The same plans split by state and county, with employer and union group plans included. CMS hides counts of 10 or fewer.
Medicare Advantage members in IllinoisLine chart, January 2023 to September 2026. Illinois: 1.1M in September 2026. Shaded bands mark months with no data.700K800K900K1M1.1M2023202420252026Illinois1.1M
Medicare Advantage members in IllinoisLine chart, January 2023 to September 2026. Illinois: 1.1M in September 2026. Shaded bands mark months with no data.700K800K900K1M1.1M20232025Illinois1.1M
  • Illinois
  • Shaded: no data that month
View the data table
Medicare Advantage members in Illinois: values by month
MonthIllinois
Sep 20261.1M
Aug 20261.1M
Jul 20261.09M
Jun 20261.09M
May 20261.09M
Apr 20261.09M
Mar 20261.09M
Feb 20261.08M
Jan 20261.06M
Dec 20251.08M
Nov 20251.08M
Oct 20251.08M
Sep 20251.08M
Aug 20251.08M
Jul 20251.07M
Jun 20251.07M
May 20251.07M
Apr 20251.06M
Mar 20251.06M
Feb 20251.06M
Jan 20251.05M
Dec 20241.04M
Nov 20241.04M
Oct 20241.04M
Sep 20241.04M
Aug 20241.04M
Jul 20241.03M
Jun 20241.03M
May 20241.04M
Apr 20241.03M
Mar 20241.03M
Feb 20241.03M
Jan 20241.02M
Dec 2023–
Nov 2023979K
Oct 2023975K
Sep 2023972K
Aug 2023968K
Jul 2023–
Jun 2023957K
May 2023953K
Apr 2023949K
Mar 2023945K
Feb 2023929K
Jan 2023796K

County file · Sep 2026. Employer group plans included.

Illinois and the nation, Jan 2023 = 100

Each line is members divided by members in the start month, times 100.

County file · Sep 2026
CMS state, county and plan-type file (SCP). The same plans split by state and county, with employer and union group plans included. CMS hides counts of 10 or fewer.
Illinois and the nation, Jan 2023 = 100Line chart, January 2023 to September 2026. Illinois: 138 in September 2026. National (same jurisdictions each month): 117.8 in September 2026. Shaded bands mark months with no data.1001101201301402023202420252026Illinois138National117.8
Illinois and the nation, Jan 2023 = 100Line chart, January 2023 to September 2026. Illinois: 138 in September 2026. National (same jurisdictions each month): 117.8 in September 2026. Shaded bands mark months with no data.10011012013014020232025Illinois138National117.8
  • Illinois
  • National (same jurisdictions each month)
  • Shaded: no data that month
View the data table
Illinois and the nation, Jan 2023 = 100: values by month
MonthIllinoisNational (same jurisdictions each month)
Sep 2026138117.8
Aug 2026137.8117.8
Jul 2026137.6117.5
Jun 2026137.3117.4
May 2026137.4117.2
Apr 2026137116.9
Mar 2026136.8116.7
Feb 2026135.9116.3
Jan 2026133.8114.7
Dec 2025135.5115.9
Nov 2025135.7115.9
Oct 2025135.5115.7
Sep 2025135.4115.5
Aug 2025135.2115.3
Jul 2025134.5115
Jun 2025134.1114.8
May 2025133.9114.4
Apr 2025133.6114.2
Mar 2025133.3113.8
Feb 2025133113.4
Jan 2025131.5111.9
Dec 2024130.9112
Nov 2024130.8112
Oct 2024130.8111.7
Sep 2024130.7111.5
Aug 2024130.2111.2
Jul 2024130.1110.9
Jun 2024129.8110.7
May 2024130.4110.5
Apr 2024129.6110
Mar 2024129.3109.7
Feb 2024129.2109.3
Jan 2024128.2108.7
Dec 2023––
Nov 2023123105.9
Oct 2023122.5105.6
Sep 2023122.1105.2
Aug 2023121.6104.9
Jul 2023––
Jun 2023120.2104.1
May 2023119.7103.8
Apr 2023119.2103.4
Mar 2023118.8103
Feb 2023116.7102.2
Jan 2023100100

County file · Sep 2026. National line sums the jurisdictions that report in every month.

Individual plans

Individual plans leave out employer and union group coverage, so counts are smaller than in the county file.

Carrier share in Illinois

Share of members whose contract has a carrier label, September 2026 against September 2025.

Contract file · Sep 2026
CMS contract file (SCC). All Medicare Advantage contracts, with employer and union group plans included. It still lists Connecticut and Alaska.

Aetna/CVS leads with 31.7% of members who have a carrier label (contract file, September 2026).

Aetna/CVS lost 2.3 points in 12 months; most of that change came in January 2026.

Humana gained 4.3 points in 12 months; most of that change came in January 2026.

UnitedHealthcare and Humana together hold 51.1%, up 1.0 points from Sep 2025.

The market is less concentrated than a year earlier (direction only; the level depends on how carriers are grouped).

Carrier share, Sep 2025 to Sep 2026

Percent of members with a carrier label. Largest carriers.

Carrier share, Sep 2025 to Sep 2026Slope chart comparing Sep 2025 with Sep 2026. Aetna/CVS: 34.1% to 31.7%; Humana: 26.6% to 30.9%; UnitedHealthcare: 23.4% to 20.2%; HCSC/BCBS: 8.2% to 6.3%; Centene/Wellcare: 2.8% to 4.5%; Zing Health: 1.6% to 1.8%.Sep 2025Sep 2026Aetna/CVS 34.1%31.7% Aetna/CVSHumana 26.6%30.9% HumanaUnitedHealthcare 23.4%20.2% UnitedHealthcareHCSC/BCBS 8.2%6.3% HCSC/BCBSCentene/Wellcare 2.8%4.5% Centene/WellcareZing Health 1.6%1.8% Zing Health
Carrier share, Sep 2025 to Sep 2026Slope chart comparing Sep 2025 with Sep 2026. Aetna/CVS: 34.1% to 31.7%; Humana: 26.6% to 30.9%; UnitedHealthcare: 23.4% to 20.2%; HCSC/BCBS: 8.2% to 6.3%; Centene/Wellcare: 2.8% to 4.5%; Zing Health: 1.6% to 1.8%.Sep 2025Sep 2026Aetna 34.1%31.7%Humana 26.6%30.9%UHC 23.4%20.2%Blue Cross 8.2%6.3%Centene 2.8%4.5%Zing 1.6%1.8%
View the data table
Carrier share, Sep 2025 to Sep 2026: Sep 2025 and Sep 2026
NameSep 2025Sep 2026Change
Aetna/CVS34.1%31.7%−2.3 pts
Humana26.6%30.9%+4.3 pts
UnitedHealthcare23.4%20.2%−3.3 pts
HCSC/BCBS8.2%6.3%−1.9 pts
Centene/Wellcare2.8%4.5%+1.6 pts
Zing Health1.6%1.8%+0.1 pts

Contract file · Sep 2026. Employer group plans included.

Carrier share of Medicare Advantage members with a carrier label, Illinois, September 2026
CarrierShare, Sep 2026Share, Sep 2025ChangeMembers
Aetna/CVS31.7%34.1%−2.3 pts345,202
Humana30.9%26.6%+4.3 pts336,292
UnitedHealthcare20.2%23.4%−3.3 pts219,628
HCSC/BCBS6.3%8.2%−1.9 pts68,377
Centene/Wellcare4.5%2.8%+1.6 pts48,582
Zing Health1.8%1.6%+0.1 pts19,236
Molina1.4%0.0%+1.4 pts15,120
Devoted Health1.3%0.9%+0.5 pts14,536
Lumeris Group Holdings Corporation1.3%1.2%+0.1 pts13,844
All other carriers0.5%––5,651
Medical Associates Clinic, P.C.0.2%0.2%0.0 pts1,996
Group 1001–0.3%––

Insurer not assigned in CMS data: 0.6% of all members in Sep 2026, 10.9% in Sep 2025. Shares leave these members out. The unassigned share is above 3%, so treat share changes as rough. Contract IDs are renumbered each January, so this page follows carriers, not contracts. A contract that serves several states carries one carrier label, so a carrier can appear in a state where it is not a local plan. See the carrier view for the whole nation.

Biggest counties in Illinois

Individual plan members and the 12-month change for each county, from county data.

Individual MA · Sep 2026
Individual Medicare Advantage plans (IND), from county data. Employer and union group plans are left out, so counts are smaller than in the other two files.
Biggest counties in Illinois by individual Medicare Advantage members, September 2026
CountyMembers12-month changeLeading carrierLeader's share
Cook327,148+2.4%Humana41.3%
DuPage52,181+2.4%Humana53.1%
Will36,517+3.2%Humana49.9%
Lake34,909+4.3%Humana55.0%
Winnebago31,289+2.8%Aetna/CVS49.3%
Kane27,744+1.7%Humana46.2%
Madison25,599+2.5%UnitedHealthcare47.0%
St. Clair25,184+1.7%UnitedHealthcare46.0%
McHenry17,419+5.4%Humana54.8%
Peoria16,067+1.3%Humana46.3%

Browse all counties.

Common questions

How many people have Medicare Advantage in Illinois?

Illinois had 1,098,001 members in September 2026, by the CMS county file (employer group plans included). Individual plans, which leave out employer group coverage, had 809,601 members in September 2026.

Is Medicare Advantage growing in Illinois?

Enrollment is up 1.9% from Sep 2025 to Sep 2026, close to the national 2.0%. Among individual plans, which leave out employer group coverage, enrollment is up 2.7% in the 12 months to September 2026.

Which carrier has the most Medicare Advantage members in Illinois?

Aetna/CVS leads with 31.7% of members who have a carrier label (contract file, September 2026). UnitedHealthcare and Humana together hold 51.1%, up 1.0 points from Sep 2025. Shares leave out members whose contract has no carrier label: 0.6% of members.

Cite and download

Cite this page

Senior Deal Club Standards Desk. Medicare Advantage Enrollment in Illinois, data as of September 2026. Source: CMS public enrollment files. https://www.seniordealclub.com/medicare-advantage/enrollment/states/illinois

Download Illinois CSV

Data: CMS public enrollment files, in a monthly snapshot processed by TapQuality. Senior Deal Club is not affiliated with Medicare or any government agency.

These pages are educational. They are not plan advice. How the numbers are built · Editorial policy