Medicare in Illinois
May 20, 2026
Illinois Medicare quick facts (2026)
- Beneficiaries: Roughly 2.4 million Illinois residents are enrolled in Medicare.
- Active Advantage carriers: UnitedHealthcare, Humana, Aetna, Blue Cross Blue Shield of Illinois (Health Care Service Corp.), Cigna, WellCare, and others.
- State Medicaid program: Illinois Medicaid (Healthcare and Family Services) — relevant for dual-eligible coordination.
- SHIP resource: Illinois SHIP (Senior Health Insurance Program) offers free unbiased counseling.
Common Illinois Medicare questions
Q: When can I enroll in Medicare in Illinois?
A: Federal calendar applies. Your 7-month Initial Enrollment Period sits around your 65th birthday; the Annual Enrollment Period runs October 15 – December 7, 2026.
Q: Can I switch Medigap plans in Illinois without underwriting?
A: Outside of the federal 6-month Medigap Open Enrollment Period and guaranteed-issue triggers, switching usually requires medical underwriting in Illinois. Confirm any current state protections with the Illinois Department of Insurance.
Q: I'm under 65 on Medicare in Illinois — can I get Medigap?
A: Illinois requires Medigap insurers to make at least one plan available to under-65 Medicare beneficiaries, though premiums may be higher than for those 65+.
Q: Where can I get unbiased Medicare help in Illinois?
A: The state's SHIP program offers free one-on-one counseling. We can also help you frame the right questions before you call a licensed agent.
Run the numbers for your situation: enrollment calculator · IRMAA calculator · Part D cost calculator.
Medicare in Illinois — plans, enrollment, and how to compare.
What Illinois residents should know about Medicare Advantage, Medicare Supplement, and Part D — and how plan availability is different in Illinois.
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Medicare basics in Illinois
Medicare is a federal program, so the core rules are the same in Illinois as everywhere else — but the specific plans available, premiums, and carrier networks vary by ZIP code and by county.
Most Illinois residents become eligible for Medicare at 65 through Social Security. See our eligibility guide for the full rules including disability and ESRD.
For the 7-month enrollment window timeline, see Turning 65.
What Illinois residents typically compare
- Medicare Advantage — Many Illinois counties have 20-50+ Advantage plans to choose from. Plans, premiums, and extras vary by county.
- Medicare Supplement (Medigap) — Plans are standardized federally, but premium pricing and underwriting rules vary by state. Illinois has its own Medigap pricing rules.
- Part D prescription drug plans — Available statewide, but formularies (covered drug lists) and preferred pharmacy networks differ by plan.
See Advantage vs. Supplement for the side-by-side framework.
Illinois Medigap timing rules
The federal Medigap Open Enrollment window is the same everywhere — 6 months starting the month you turn 65 AND have Part B. During that window, no medical underwriting.
Outside that window, most states (including Illinois unless otherwise noted) allow Medigap carriers to use medical underwriting — meaning they can deny you or charge more based on health. A few states have year-round guaranteed-issue rules. Check Illinois's State Health Insurance Assistance Program (SHIP) for current rules.
See our switching from Advantage to Medigap guide for the timing trap.
How to compare plans in Illinois
- Confirm your ZIP code — plans differ within Illinois by county
- List your prescriptions and check each one on the plan's formulary
- Confirm your doctors are in-network
- Compare premium + deductible + maximum out-of-pocket
- Check star ratings for plans you are weighing
- Ask about prior authorization requirements (common on Advantage)
Use our comparison framework to keep it organized.