Best Medicare Supplement Plans in Illinois (2026)

Illinois has one of the more competitive Medigap markets in the Midwest. Federal law standardizes plan benefits across all 50 states, so the only variables that differ between Illinois and a neighboring state like Indiana or Wisconsin are premium levels, insurer participation and pricing method mix. Illinois seniors aren't subject to any state-specific Medigap rating restrictions beyond federal rules, which means Attained Age Pricing is the dominant model here. Premiums start lower at 65 and rise each year. That matters more in Illinois than in states where community-rated plans are more common, because the gap between your age-65 rate and your age-75 rate can be wide under Attained Age structures. 

If you're weighing a Medicare Advantage plan as an alternative, our Best Medicare Advantage Plans in Illinois page compares network restrictions and out-of-pocket costs side by side.

When we pulled rates for all 10 standardized plan types across Illinois Medicare Supplement insurers, the result was consistent, nearly every top-ranked insurer uses Attained Age Pricing, which means premiums rise as you age. Transamerica is the exception for Plan K, using Issue Age Pricing that locks your rate at enrollment. Illinois seniors who plan to hold a policy for 10 or more years should weigh the pricing method against the monthly rate before choosing.

Our analysis found monthly premiums ranging from $96 to $208 for 65-year-olds across 10 standardized plan types. MedMutual Protect ranks first for three popular plans. Plan N is the cheapest at $101 monthly, followed by Plan G at $144 and Plan F at $164. USAA holds the lowest Plan A rate at $121 monthly. Illinois beneficiaries choosing these insurers save $21 to $155 monthly compared to state averages.

*These rates reflect Medigap premiums for 65-year-olds. 

For most 65-year-olds enrolling in Illinois for the first time, MedMutual Protect Plan G at $144 monthly is the right starting point because Plan G covers everything except the Part B deductible. After that deductible, your out-of-pocket maximum is essentially zero. At $109 below the state average for Plan G, MedMutual Protect's rate advantage is large enough to outweigh any service-tier difference with higher-priced competitors.

If you plan to hold this policy for 15 or more years and rate stability matters more than the lowest entry price, Transamerica's Issue Age Pricing on Plan K is the only option that locks your rate at enrollment. Plan K costs $96 monthly at 65, but it covers only 50% of most out-of-pocket costs, so it's the right trade-off only for seniors with strong savings and low expected health care use.

USAA Plan A is $121 monthly, the lowest rate for that plan type on this page. Eligibility is limited to military members and their families. Military-eligible seniors should still compare. Plan A's coverage is thinner than Plan G, so the lower price reflects lower protection, not a better value.

Everyone's coverage needs are different, so your best option may differ from these popular choices. Explore the table below to find the Illinois Medicare Supplement company that matches your specific situation.

Illinois residents age 65 pay $117 to $319 monthly for Medicare Supplement insurance depending on plan type. Monthly costs vary by $202 between the cheapest and most expensive plans.

Plan K costs $117 monthly, the lowest average rate. Plan F costs $319 monthly, the highest average. Plan G averages $253 monthly. Additional options include Plan M at $145, Plan L at $182 and Plan D at $225 monthly.

The $202 monthly spread between Plan K and Plan F is the widest cost gap in MoneyGeek's Illinois rate data. A 65-year-old who chooses Plan K over Plan F saves $2,424 per year in premiums. Plan K covers only 50% of out-of-pocket costs, so those savings disappear fast with regular health care use. For seniors with limited health care use and at least $3,000 in accessible savings, Plan K's math works. For anyone managing a chronic condition or taking regular prescription medications, the premium savings erode quickly against the cost-sharing exposure.

Federal law standardizes Medicare Supplement plans. Plan G from Company A covers exactly what Plan G from Company B covers, meaning premium amounts vary while benefits stay the same across insurers. Compare what each plan type covers to choose the right balance between premiums and out-of-pocket expenses.

Learn More: What Does Medicare Cover and Not Cover?

Your Medicare Supplement insurer selection should focus on cost differences, service quality and company reliability since the benefits are identical for all plan types.

Illinois residents comparing Medigap plans can access these resources: 

• Senior Health Insurance Program (SHIP): Free statewide health insurance counseling for Medicare beneficiaries and caregivers through Illinois Department on Aging. Trained volunteers and certified counselors meet one-on-one for confidential sessions. SHIP produces annual Medicare Supplement Premium Comparison Guides. Senior HelpLine: 1-800-252-8966 (TTY: 1-888-206-1327). Email: aging.ship@illinois.gov. SHIP counselors educate about Medicare Parts A and B, Medicare Supplements, Medicare Advantage plans and Part D prescription drugs.
• Illinois Department of Insurance - Consumer Services: File complaints online or request forms through Consumer Assistance Hotline: 866-445-5364. Written complaints required. Illinois law gives insurers 21 days to respond. Investigations take four to six weeks. Complaints remain confidential records. Mail to 320 W. Washington Street, Springfield, IL 62767. Chicago office: 115 S. LaSalle Street, 13th Floor, Chicago, IL 60603, (312) 814-2420.
• Illinois Area Agencies on Aging: Thirteen Planning and Service Areas covering Illinois' 102 counties, managed by 12 nonprofit corporations and Chicago's Department of Family and Support Services. Agencies contract with local organizations to provide senior services. Contact Senior HelpLine: 1-800-252-8966 for your local agency and available programs.
• Medicare.gov: Enter your ZIP code in the Plan Finder to browse Medigap policies sold in Illinois and examine coverage details side by side.

If you’re unsure how Medigap coverage works in Illinois, the answers below address common concerns.

MoneyGeek collected rate data for all Medicare Supplement plans available in Illinois using the plan browsing tool at Medicare.gov. Quotes were pulled for a non-tobacco user in the Chicago metropolitan area ZIP code. Data reflects rates for 65-year-olds and 75-year-olds. Rates were collected in May 2026. Unless otherwise noted, the data in this article references quotes for 65-year-olds. 

We scored Medigap companies in Illinois based on three main categories to create a weighted score out of 5:

• Affordability (50%): Providers with the lowest monthly cost score higher.
• Pricing style (20%): Medigap insurers use three methods to determine premiums: Community Pricing, Issue-Age Pricing and Attained Age Pricing. We gave higher scores for pricing styles that are more stable and equitable: Community Pricing 1.0, Issue-Age Pricing 0.8, Attained-Age Pricing 0.6. Using this scaling, a slightly higher-cost community-rated plan can still score higher overall than a cheaper but more volatile attained-age plan.
• Plan availability (30%): Providers with a wider range of plan types score higher. Extra weight goes to the most popular plan types: Plan G, Plan F and Plan N.