Guide · Health insurance
Evaluate health insurers using government data
A framework for assessing health insurers with NAIC complaint ratios, CMS denial rates, and prior-authorization metrics, beyond star ratings and marketing.
- 37%
- Highest denial
- 3%
- Lowest denial
- 3
- Data pillars
According to the U.S. Centers for Medicare & Medicaid Services Transparency in Coverage Public Use File (plan year 2026) and NAIC Market Conduct Annual Statement data (2024), PlainInsurer analyzed more than 1,000,000 marketplace claims alongside complaint records from all 50 states to build this three-pillar framework. See our methodology for the full computation.
The short answer
The best predictor of how a health insurer will treat you is how it already treats its policyholders, measured by complaint ratios, claim-denial rates, and prior-authorization practices, not marketing. Three independent government signals, layered, beat any single number.
- 3
- government data pillars
- NAIC
- complaint ratio
- CMS
- denial + PA rate
- A–F
- composite grade
Each signal is computed by an upstream regulator using a documented methodology, so it is comparable across insurers. NAIC MCAS 2024 + CMS Transparency in Coverage PY2026. Data as of August 2026.
Claim-denial rates swing widely between insurers
Highest and lowest claim-denial rates among large marketplace health insurers
- CareSource North Carolin
CareSource North Carolina Co.: 37.0% denied
37 % of claims denied
- Select Health of South C
Select Health of South Carolina: 36.5% denied
37 % of claims denied
- Oscar Buckeye State Insu
Oscar Buckeye State Insurance Corp.: 36.4% denied
36 % of claims denied
- UnitedHealthcare Communi
UnitedHealthcare Community Plan, Inc.: 35.6% denied
36 % of claims denied
- Oscar Health Plan
Oscar Health Plan, Inc.: 34.6% denied
35 % of claims denied
- UnitedHealthcare of Okla
UnitedHealthcare of Oklahoma, Inc.: 33.7% denied
34 % of claims denied
- Avera Health Plans 4
Avera Health Plans, Inc.: 3.5% denied
4 % of claims denied
- Sanford Health Plan 6
Sanford Health Plan: 5.5% denied
6 % of claims denied
- HealthPartners 7
HealthPartners Insurance Company: 6.6% denied
7 % of claims denied
- Capital Health Plan 7
Capital Health Plan: 7.1% denied
7 % of claims denied
- Matthew Thornton Hlth Pl 8
Matthew Thornton Hlth Plan(Anthem BCBS): 8.0% denied
8 % of claims denied
- Providence Health Plan 8
Providence Health Plan: 8.3% denied
8 % of claims denied
What this shows The same claim could be paid by one insurer and denied by another. Pair the denial rate with the complaint ratio and prior-auth practices to read the full consumer-friction picture.
Why government data is more reliable than star ratings
Health-insurance star ratings combine quality measures with member-satisfaction surveys. While useful, they can be influenced by the demographic composition of a plan's membership and the plan's investment in survey-boosting initiatives. Regulatory complaint data from NAIC and CMS captures a different dimension: how many policyholders filed formal complaints or had claims denied. These are observable administrative outcomes, not survey responses. PlainInsurer indexes these columns across 215 tracked insurers so peers can be compared on the same public metrics.
The three pillars of insurer evaluation
Complaint ratio (NAIC MCAS): how many formal complaints an insurer receives relative to its market share. Ratios consistently above 1.5 mark elevated consumer-friction relative to peers in the same line.
Claim denial rate (CMS): what percentage of claims the insurer denies. This measures how often the company refuses coverage for ordered care. High denial rates correlate with more administrative friction even when many denials are later overturned on appeal.
Prior-authorization denial rate (CMS, for MA plans): how often the insurer denies prior-authorization requests. Prior authorization gates many medications, procedures, and specialist referrals; elevated denial rates appear as delayed or blocked care in OIG and CMS reporting. The metric is especially central when reading Medicare Advantage contracts.
Reading the PlainInsurer reputation grade
What it tells you: the A–F grade combines all three metrics into a single composite score, normalized against the insurer population. An "A" means the company performs better than most peers on complaints, denials, and prior authorizations; an "F" means worse.
What it does not tell you: whether the company's network includes a specific clinician set, whether a premium fits a household budget, or whether coverage terms match a specific need. The grade measures claims and complaint outcomes, not plan fit.
How the grade is used in this registry: the grade is a peer filter among contracts that already share a coverage class. Premium differences and grade differences are separate axes; the page does not recommend trading one for the other.
State-level variation matters
Insurance regulation is state-based, and insurer behavior can vary significantly by state. A company with a good national complaint ratio may have elevated complaints in one state due to local market conditions, regulatory environment, or network-adequacy issues. Each company profile page includes state rows when the underlying filings support them.
Network adequacy: the missing metric
One critical dimension that complaint data and denial rates do not capture is network adequacy, whether the insurer has sufficient in-network providers in a given area. An insurer can have excellent complaint ratios but limited specialist access in a county. Network adequacy issues are a common reason members experience access problems that never show up in denial statistics, because no claim is filed when an appointment cannot be obtained. Network directories and provider directories sit outside the NAIC/CMS columns this registry indexes.
Why layering matters more than any single signal
A single quantitative signal can flag a problem but cannot distinguish between causes. A high complaint ratio can reflect coverage disputes, claims-handling friction, network-access issues, or aggressive marketing. Layering complaint data with denial rate, prior-authorization activity, and appeals-overturn rate progressively localizes the friction source. When multiple signals point the same direction, the conclusion is more robust than when only one is elevated. The composite score is a useful summary, but the per-component breakdown is more informative for comparison.
What this means for the public record
Employer, marketplace, and Medicare option lists name candidate insurers. Each can be looked up on PlainInsurer for reputation grade, complaint ratio, and denial rate. Comparisons stay inside one line (health to health, not health to auto). State rows refine national grades. Annual refreshes of the upstream NAIC/CMS files change the columns; renewal-period reads should use the current vintage, not a prior year's snapshot.
What the registry surfaces
Three public columns that compose the peer comparison.
- Insurer profiles list grade, complaint ratio, and denial rate from NAIC/CMS. Browse insurers
- Rankings keep health-line peers in one table. See rankings
- Medicare Advantage prior-authorization denial rates are a separate CMS column. Prior auth guide
This guide describes a quantitative comparison framework for reading public regulatory data on health insurers. It is not advice about which specific plan to enroll in.