Illinois Medicare, by the Numbers

Medicare Enrollment by County

Counties covered by our city pages (29 counties, 2,054,203 beneficiaries). Each county links to its anchor city page.

Statewide, 43.5% of beneficiaries chose Medicare Advantage in 2025. Counties above that line see more prior authorizations and more denials worth appealing; counties below it lean on Medigap timing. Illinois added a Medigap birthday rule in 2025, giving people 65 to 75 who already hold a policy a 45-day window each year, starting on their birthday, to switch to an equal-or-lesser plan with their own insurer or an affiliate without underwriting, and it requires every insurer to offer at least one plan on a guaranteed-issue basis to under-65 beneficiaries who qualify through disability, though at the top rate charged to 65-and-older enrollees, so getting the timing right still counts. About 9.8% of Illinois seniors live below the poverty line, the group most likely to qualify for unclaimed help: federal Extra Help and the Medicare Savings Programs, which the Department of Healthcare and Family Services runs with an income and asset test (Illinois has no state drug program of its own). For the full rundown, sources included, see our Illinois patient advocacy hub.