Medicare in Illinois: 2026 Plans, Costs, and Enrollment Guide

Illinois Medicare Snapshot

Illinois is a large and diverse Medicare market — from Chicago's dense urban counties to rural downstate communities — with approximately 2.3M Medicare beneficiaries (per KFF State Health Facts). Medicare Advantage penetration sits at roughly 34% of Illinois beneficiaries, meaning about two in three Illinois Medicare enrollees remain on Original Medicare. That said, the MA market is competitive and growing: 159 unique plans from 17 carriers are available in 2026, covering every county with MA presence (CMS CY2026 Landscape, March 2026 release).

The average consolidated MA premium across all Illinois plans is $15.64/month, with a median of $0 — over half of plans carry no monthly premium beyond the standard Medicare Part B premium. Average CMS star rating is 3.57 out of 5.

Plan Types Available in Illinois

Medicare Advantage (Part C)

Medicare Advantage plans bundle your Part A, Part B, and usually Part D drug coverage into one private plan. In Illinois, 159 MA plans are available for 2026 from 17 carriers (CMS CY2026 Landscape). Plan type mix: 69 PPO, 28 HMO, 22 HMO-POS, 13 HMO C-SNP (chronic condition special needs), 8 HMO D-SNP (dual-eligible special needs), 2 PFFS, and 2 Regional PPO, among others.

County availability ranges significantly: Cook County has 78 MA plans — the most of any county — while rural Massac County has 16. All 102 counties with MA coverage have at least one plan available.

Medigap (Medicare Supplement)

Medigap works alongside Original Medicare (Parts A and B) to cover out-of-pocket costs like deductibles, coinsurance, and copays. Illinois has 44 Medigap carriers offering all 12 standardized plan letters (A, B, C, D, F, G, HDF, HDG, K, L, M, N). Plan G and Plan N each have 43 carriers available — the widest selection among active plans. Plan F has 43 carriers but is closed to new enrollees as of January 1, 2020 (MACRA) — it remains available only to those who were Medicare-eligible before that date.

Medigap does not include prescription drug coverage — you'll need a separate Part D plan. See our MA vs Medigap comparison →

Standalone Part D (Prescription Drug Plans)

Illinois is CMS PDP Region 17 — Illinois alone. For 2026, there are 12 standalone PDP plans from 5 carriers: HealthSpring (4 plans), Humana (3), UnitedHealthcare (2), Wellcare (2), and Aetna Medicare (1). Average total premium is $61.55/month; premiums range from $0 to $119.70/month (CMS CY2026 Landscape).

Costs in Illinois

Medicare Advantage Premiums

The average consolidated MA premium in Illinois is $15.64/month (CMS CY2026 Landscape). A consolidated premium includes any Part C and Part D premium rolled together. The median is $0, meaning the majority of Illinois MA plans have no monthly plan premium beyond what you already pay for Medicare Part B ($202.90/month standard in 2026 per CMS).

The top three carriers by plan count are Humana (32 plans), Aetna Medicare (27 plans), and UnitedHealthcare (23 plans) (CMS CY2026 Landscape). Average star rating across rated plans is 3.57 — mid-market quality overall, with 18 plans rated 4.5 stars and one plan at 5 stars.

Medigap Premiums — Plan G and HDG

Medigap premiums vary by carrier, age, gender, tobacco use, and rating method (attained-age, issue-age, or community-rated). Across the 42 carriers offering Plan G in Illinois (non-tobacco rates, ages 65–85; 43 total Plan G carriers statewide), monthly premiums range from approximately $122 to $692/month (TPP internal data, CY2026; methodology: non-tobacco rates, ages 65–85, all carriers offering Plan G). Your individual quote will depend on your age and carrier selection.

High-Deductible Plan G (HDG) — a lower-premium option with a $2,950 deductible in 2026 (CMS-published annual HDG/HDF deductible) — is offered by 35 Illinois carriers. HDG carrier offerings range from approximately $113 to $644/month across ages 65–85, non-tobacco rates (TPP internal data, CY2026). HDG works well for beneficiaries who want catastrophic protection at a lower monthly cost and can absorb the deductible.

Part D Costs and the LIS Benchmark

For 2026, Illinois Part D premiums average $61.55/month across 12 standalone PDP plans, with a range of $0 to $119.70/month. The CMS Low Income Subsidy (LIS / Extra Help) benchmark premium for PDP Region 17 (Illinois) is $15.20/month — the maximum CMS will subsidize toward a Part D premium for eligible low-income beneficiaries. Two plans (Wellcare Classic PDP and Humana Basic Rx Plan) carry a $0 premium and qualify for LIS auto-enrollment (CMS CY2026 Regional Rates and Benchmarks PDF).

Illinois-Specific Medicare Rules

The Illinois Birthday Rule

Illinois enacted a Birthday Rule (215 ILCS 5/363, Public Act 102-0142), effective January 1, 2022, that gives Medigap policyholders ages 65–75 a 45-day window starting on their birthday each year to switch to any Medigap plan with equal or lesser benefits from their current carrier — or an affiliate of that carrier — without medical underwriting. This means Illinois beneficiaries get a guaranteed annual opportunity to shop for lower premiums on their current plan letter without risk of denial.

Key details: the switch must be to the same carrier or an affiliate of your current insurer (the 2024 IL legislation expanded the original same-carrier-only scope to include affiliated insurers), and the new plan must have equal or lesser benefits than your current plan. The rule applies only to beneficiaries ages 65–75 — anyone over age 75 is not eligible. You can use this window to move from a higher-premium plan to a lower-cost option within the same plan letter.

Medicare Savings Programs (MSPs)

Illinois offers three Medicare Savings Programs (MSPs) that help low-income Medicare beneficiaries pay for Medicare costs:

• QMB (Qualified Medicare Beneficiary): Covers Part A and Part B premiums, deductibles, and cost-sharing. Highest assistance level.
• SLMB (Specified Low-Income Medicare Beneficiary): Covers Part B premiums only.
• QI-1 (Qualifying Individual-1): Also covers Part B premiums; subject to annual appropriations.

MSP eligibility is based on income and resources. Apply through the Illinois Department of Healthcare and Family Services or contact Illinois SHIP (800-548-9034) for free enrollment assistance. MSP enrollment also automatically qualifies you for Extra Help / LIS on Part D. Learn more about MSPs →

Illinois SHIP

Illinois SHIP (State Health Insurance Assistance Program) provides free, unbiased counseling on all Medicare options. SHIP counselors help with plan comparisons, enrollment, billing issues, and appeals — at no cost to beneficiaries.

Phone: 800-548-9034
Website: https://www2.illinois.gov/aging/ship/

Enrolling in Medicare in Illinois

Standard Enrollment Periods

• Initial Enrollment Period (IEP): 7-month window centered on your 65th birthday month (3 months before, your birthday month, 3 months after). Enroll in Parts A and B at ssa.gov or call 1-800-772-1213.
• Annual Election Period (AEP): October 15 – December 7 each year. Change your Medicare Advantage or Part D plan for the following year.
• Medicare Advantage Open Enrollment Period (OEP): January 1 – March 31. Switch MA plans or return to Original Medicare once per year.
• Medigap Open Enrollment Period: 6-month window that starts the month you are both 65+ and enrolled in Part B. Guaranteed issue — insurers cannot deny you or charge more based on health history. After this window, medical underwriting applies (with the annual Illinois Birthday Rule exception for ages 65–75 to switch within the same carrier or affiliate).
• Special Enrollment Periods (SEPs):Available if you have qualifying life events such as losing employer coverage, moving out of your plan's service area, or qualifying for a low-income program. Learn more →

Illinois SHIP Counseling

Illinois SHIP has counselors available across the state — in person, by phone, and at community events. For free, one-on-one help comparing Medicare plans and navigating enrollment, contact SHIP at 800-548-9034 or visit https://www2.illinois.gov/aging/ship/.

Frequently Asked Questions