Illinois health insurers by reported claim denial rate
10 marketplace issuers in Illinois reported 2,948,254 denials on 15,026,796 in-network claims from 2023 (pooled rate 19.6%). The median rate among the 10 ranked issuers is 20.4%, against a national median of 18.3% across 32 HealthCare.gov states. Of 4,338 internal appeals filed, 34.4% were overturned.
All issuers reporting in Illinois, plan year 2025 file
| # | Issuer | Claims received | Denied | Denial rate | Appeals filed | Overturned |
|---|---|---|---|---|---|---|
| 1 | UnitedHealthcare of Illinois, Inc. | 486,710 | 181,665 | 37.3% | 691 | 39.2% |
| 2 | Molina Healthcare of Illinois, Inc. | 91,489 | 31,949 | 34.9% | 34 | 38.2% |
| 3 | Cigna HealthCare of Illinois, Inc. | 347,240 | 90,407 | 26.0% | 53 | 45.3% |
| 4 | Oscar Health Plan, Inc. | 49,013 | 10,211 | 20.8% | 722 | 33.0% |
| 5 | Blue Cross Blue Shield of Illinois | 10,556,396 | 2,169,193 | 20.5% | 2,232 | 31.1% |
| 6 | Aetna Health Inc. (a PA corp.) | 167,244 | 33,764 | 20.2% | 53 | 49.1% |
| 7 | Celtic Insurance Company | 1,681,947 | 230,759 | 13.7% | 314 | 44.6% |
| 8 | Health Alliance Medical Plans, Inc. | 1,507,897 | 187,861 | 12.5% | 221 | 39.8% |
| 9 | MercyCare HMO, Inc. | 67,263 | 7,524 | 11.2% | n/a | n/a |
| 10 | Quartz Health Benefit Plans Corporation | 71,597 | 4,921 | 6.9% | 18 | n/a |
Sorted by reported in-network denial rate. Rank is shown only for issuers with at least 1,000 in-network claims received; smaller issuers are listed without a rank. Source: CMS Transparency in Coverage PUF.
- Reporting lag: the CMS public-use file for a plan year reports claims from two plan years earlier (the PY2025 file carries 2023 claims). These are not this year's figures.
- In-network only: the denial rate is in-network claims denied divided by in-network claims received. Out-of-network claims are shown separately where the issuer reported them.
- "Denied" is broad: CMS counts every denial, including administrative denials, duplicate submissions, ineligibility, incorrect billing and partial denials, not only medical-necessity decisions.
- Issuer level: CMS reports the counts once per issuer per state and repeats them on every plan row; plan-level counts, where present, list denials only, so no per-plan rate is computed.
- Coverage: only issuers on the federally facilitated marketplace (HealthCare.gov states) report to this file. Employer plans, Medicare and Medicaid are not included.
- No inference of intent: a higher rate can reflect the issuer's mix of claims, its billing rules or its membership as much as its coverage decisions. Compare with the state median and read the N.
Source: CMS Transparency in Coverage Public Use File (Health Insurance Exchange PUFs) · data dictionary.
Denied in Illinois? What to do
- Illinois appeal rights and regulator →
- Appeal deadline calculator →
- Have Apellica prepare the appeal ($0 upfront) →
Questions
Which Illinois marketplace insurer reported the highest claim denial rate?
Among issuers with at least 1,000 in-network claims, UnitedHealthcare of Illinois, Inc. reported the highest rate in the plan year 2025 file: 37.3% (181,665 of 486,710 claims from 2023). The Illinois median is 20.4%. A high rate can reflect claim mix and billing rules as much as coverage decisions.
Does a lower denial rate mean a better plan?
Not by itself. Rates include administrative denials and depend on the issuer's membership and claim mix. Use the rate alongside network, premium, formulary and the appeal overturn rate, and read the caveats.
Where does this data come from?
The CMS Transparency in Coverage public use file for plan year 2025, which reports each issuer's 2023 in-network claims received and denied, internal appeals and external reviews for plans sold on HealthCare.gov. Apellica removed stand-alone dental issuers and computed nothing beyond the reported counts.
How do I appeal a denial in Illinois?
File an internal appeal within the deadline on your letter (at least 180 days on marketplace plans), request the plan's criteria and claim file in writing, then use Illinois's external review if the plan upholds the denial. The regulator is Illinois Department of Insurance.
Download the full table as CSV · methodology · CC BY 4.0.