CMS's own filing for Illinois
Medicare Advantage plans in Illinois, by the numbers
What CMS published about Medicare enrollment in Illinois: 5 of 5 measures filed for this state, each one a field of the state's own row with the date the file was read.
- figures published by CMS
- 5
- counts CMS withheld
- 0
- the day this file was read
- 2026-09-11
Where Illinois sits among the states
43.5% of everyone with Medicare in Illinois is in a Medicare Advantage or other health plan rather than Original Medicare. That puts Illinois 34th of 51, between Mississippi above it and Oklahoma below. Across the country the same figure runs from 62.8% in Michigan down to 3.0% in Alaska, so what counts as the ordinary choice depends on where a person lives, and this is what it is where they do.
Every measure CMS filed for Illinois
| Measure | What CMS published | Source |
|---|---|---|
| People with Medicare | In 2025, 2,452,877 people were enrolled in Medicare in Illinois. | CMS Medicare Monthly Enrollment, 2025 read September 2026 |
| In Medicare Advantage and other health plans | In 2025, 1,065,942 of them were in Medicare Advantage or another health plan rather than Original Medicare in Illinois (43.5% of everyone with Medicare in Illinois). | CMS Medicare Monthly Enrollment, 2025 read September 2026 |
| In Original Medicare | In 2025, 1,386,935 stayed in Original Medicare in Illinois (56.5% of everyone with Medicare in Illinois). | CMS Medicare Monthly Enrollment, 2025 read September 2026 |
| In a stand-alone Part D drug plan | In 2025, 1,000,263 bought drug coverage as a stand-alone Part D plan in Illinois (40.8% of everyone with Medicare in Illinois). | CMS Medicare Monthly Enrollment, 2025 read September 2026 |
| Also covered by Medicaid | In 2025, 406,389 were covered by Medicaid as well as Medicare in Illinois (16.6% of everyone with Medicare in Illinois). | CMS Medicare Monthly Enrollment, 2025 read September 2026 |
A withheld figure means CMS did not publish the count, never that the count is zero.
Cite or embed this figure
Illinois: 5 Medicare enrollment figures published by CMS and 0 counts withheld (Medicare Plan Comparison State Enrollment Index).
Cite as: "Medicare Plan Comparison State Enrollment Index: Illinois", updated 2026-09-11, https://medicareplancomparison.com/states/illinois/.
Download the Illinois figures (CSV), free to reuse with citation.