Illinois has approximately 2.3 million Medicare beneficiaries , with the largest concentrations in Cook County, the collar counties (DuPage, Kane, Lake, McHenry, Will), and the downstate metros. Medicare Advantage penetration has climbed steadily across the state and is now well above 40% in greater Chicago, though somewhat lower in rural counties.1
What Medicare covers, and what it doesn't
Medicare is health insurance. It is not long-term-care insurance. This is the single most expensive misconception in caregiving. Illinois families learn it most often when the 100-day Medicare rehab benefit ends after a hospital stay and the next bill is all-private-pay.
What Medicare does cover:
- Part A (Hospital). Inpatient stays, skilled nursing rehab for up to 100 days after a qualifying hospital admission (covered in full for first 20 days, then a daily coinsurance for days 21-100), hospice, and limited home health.
- Part B (Medical). Doctor visits, outpatient procedures, durable medical equipment, mental health, preventive care, ambulance.
- Part D (Drugs). Prescription drug coverage, either standalone or bundled into a Medicare Advantage plan.
What Medicare does not cover:
- Assisted living (any state, any setting)
- Memory care
- Custodial nursing-home care beyond the 100-day rehab window
- Long-term in-home aide hours (Medicare covers brief home health for medical recovery, not ongoing personal-care support)
- Dental, vision, or hearing in Original Medicare (many Medicare Advantage plans add some of these as extras)
Original Medicare vs. Medicare Advantage in Illinois
Every Medicare-eligible person in the US chooses between two broad structures: Original Medicare (Parts A and B, usually paired with a Medigap supplement and a Part D drug plan) or Medicare Advantage (Part C, a private plan that bundles A, B, and usually D plus extras).
Illinois Medicare Advantage penetration is solidly above 40% statewide and higher in Cook County and the collar counties, where Advantage plans compete intensely.2 Downstate counties tend to skew toward Original Medicare, partly because rural Advantage networks are thinner.
When Original Medicare + Medigap usually beats Advantage
- Your parent travels frequently or splits time across states (Illinois has a meaningful population of Florida and Arizona snowbirds). Original Medicare works nationally with any Medicare-accepting provider; Advantage plans have networks.
- Your parent has a serious or complex condition and wants unrestricted specialist access without referrals or prior authorizations.
- Your parent can afford the higher monthly premium for a Medigap supplement — in Illinois, $150–$300/month is typical for Plan G — in exchange for predictable out-of-pocket costs.
When Advantage usually beats Original Medicare
- Your parent lives in one Illinois county year-round and is generally healthy.
- Original Medicare Part B premium + Medigap premium + Part D premium exceeds your parent's budget, and a $0-premium Advantage plan is available.
- Your parent values the extras — dental, vision, hearing, gym — that many Illinois Advantage plans bundle in.
Medigap in Illinois
If your parent chooses Original Medicare, they almost certainly also want a Medigap (Medicare Supplement) policy to cover the deductibles and coinsurance that Original Medicare leaves behind. Medigap plans are federally standardized— Plan G in Illinois offers the same benefits as Plan G in any other state — but Illinois pricing and switching rules have specific details:
- Illinois is generally age-rated, meaning premiums rise as your parent ages. (Some states — Connecticut, New York, Massachusetts — require "community rating," where premiums don't rise with age. Illinois does not.)
- Guaranteed issue applies during the 6-month Initial Enrollment Period, when your parent turns 65 or first enrolls in Medicare Part B. Outside that window, insurers can use medical underwriting to deny coverage or charge more.
- Illinois does not have an annual no-underwriting switching window for Medigap (unlike California or Oregon). Once your parent picks a plan, switching can require requalifying medically.3
MyCare Illinois for dual-eligibles
For Illinois residents enrolled in both Medicare and Medicaid (dual-eligibles), MyCare Illinoisoffers integrated managed care that coordinates Medicare benefits, Medicaid benefits, prescription drugs, and long-term services and supports through a single MCO. The program operates in a defined set of counties — primarily Cook and the collar counties, plus some central Illinois counties.
Many newly-eligible duals are automatically enrolled with the option to opt out and return to traditional Medicare + Medicaid coverage. The opt-out timeline matters; missing it means another year before the next enrollment window. SHIP counselors can walk families through the comparison.4
Medicare Savings Programs (MSPs) in Illinois
If your parent has limited income, they may qualify for one of the federal Medicare Savings Programs, administered in Illinois by HFS:
- QMB (Qualified Medicare Beneficiary). Pays Part A and Part B premiums, deductibles, and coinsurance. Income limit ~$1,255/month individual (2026).
- SLMB (Specified Low-Income Beneficiary). Pays Part B premium only. Income limit ~$1,506/month individual.
- QI (Qualifying Individual). Pays Part B premium. Income limit ~$1,695/month individual.
Many Illinois seniors who qualify never apply because the application is opaque and HFS isn't proactive about outreach. SHIP counselors can help.
Annual Enrollment Period (AEP) in Illinois
Medicare AEP runs from October 15 through December 7 each year. During this window your parent can:
- Switch from Original Medicare to Medicare Advantage (or vice versa)
- Switch from one Advantage plan to another
- Add, drop, or switch a standalone Part D plan
Cook County and the collar counties see intense AEP marketing — TV ads, mailers, in-person events. The single most important thing to know is that most ads are designed to drive enrollment in a specific plan, not to help your parent compare plans. The right comparison tool is Medicare.gov's Plan Finder, which lets you enter your parent's zip code, current prescriptions, and preferred providers, then ranks every plan available to them by total annual cost.5
There is also a Medicare Advantage Open Enrollment Period (MA OEP) from January 1 through March 31 each year, during which someone already on Advantage can switch to a different Advantage plan or back to Original Medicare with Part D.
Where to get free help in Illinois
SHIP(Senior Health Insurance Program) is Illinois's federally-funded State Health Insurance Assistance Program, administered by the Department on Aging. Trained counselors across Illinois provide free, unbiased Medicare counseling — they don't sell plans, take commissions, or represent any insurer. Call 1-800-252-8966 (the Senior HelpLine) to find a counselor near your parent.
For specific Medicaid-related questions where Medicaid and Medicare interact (dual-eligibility, long-term-care benefits), see our Illinois Medicaid guide.