Comparing Medicare Advantage Plans: Prior Auth Rates, Denial Rates by Insurer (2026)" class="auto-link">Denial Rates, and Star Ratings

Medicare Advantage (Part C) allows Medicare beneficiaries to receive their Medicare benefits through a private insurance company rather than through traditional fee-for-service Medicare. More than 33 million Americans — roughly half of all Medicare beneficiaries — are enrolled in Medicare Advantage plans. But not all MA plans are created equal, and the differences in prior authorization rates, denial rates, and quality ratings are significant enough to affect your health outcomes and out-of-pocket costs.

What Medicare Advantage Plans Cover

MA plans must cover all services covered by traditional Medicare (Parts A and B). Most also include prescription drug coverage (Part D) and many add supplemental benefits like dental, vision, and hearing that traditional Medicare does not cover.

In exchange for these extras, members must use the plan's provider network, follow its prior authorization rules, and accept its coverage determinations. The plan — not Medicare directly — decides whether specific services are covered.

The Prior Authorization Problem in Medicare Advantage

Prior authorization (PA) in Medicare Advantage has become one of the most significant policy debates in US healthcare. Unlike traditional Medicare, which does not require PA for most services, MA plans impose PA requirements on a wide range of services.

A 2022 report by the HHS Office of Inspector General found that MA plans denied prior authorization requests and payment claims that met Medicare coverage rules, and that many of those denials were reversed on appeal. Specific findings:

• One in eight prior authorization requests was denied in the studied period.
• Many denials were for services that traditional Medicare would have covered.
• Denial rates varied widely among plans — from under 2% to over 25% of PA requests.

Which Insurers Have the Highest and Lowest Denial Rates?

CMS collects and publishes prior authorization and appeals data for Medicare Advantage plans. Based on CMS and OIG data:

Higher denial rate patterns have been documented at:

• UnitedHealthcare (particularly through NaviMed for post-acute care)
• Humana (OIG 2022 report findings)
• Centene/WellCare subsidiaries in several markets
• Several regional Blue Cross Blue Shield Medicare Advantage plans

Lower denial rate patterns have been associated with:

• Some Kaiser Permanente MA plans (though coverage is geographically limited)
• SCAN Health Plan (California)
• Some non-profit MA plan options in local markets

These patterns shift year to year as plans respond to regulatory scrutiny and as CMS enforcement changes.

CMS Star Ratings: What They Measure

CMS publishes annual Star Ratings (1–5 stars) for each Medicare Advantage plan. Star ratings incorporate:

• Clinical quality measures: Breast cancer screening rates, diabetes management, controlling blood pressure.
• Member experience measures: How well plans communicate, respond to member issues, and handle appeals.
• Administrative measures: Including appeals and grievance outcomes.

Plans rated 4 stars or higher receive quality bonus payments from CMS, creating financial incentive to maintain quality. Plans rated below 3 stars for multiple years can face sanctions.

How to use star ratings in plan selection:

• 4 and 5 stars indicate strong performance across quality dimensions.
• 3 stars is average — some measures may be strong, others weak.
• Below 3 stars warrants scrutiny; some measures may indicate problematic denial patterns.

The Medicare Plan Finder tool (medicare.gov) allows you to compare plans in your zip code by star rating, premium, and covered benefits.

Prior Auth Transparency Rule

Effective 2024, CMS implemented new rules requiring MA plans to:

• Publish prior authorization requirements publicly.
• Provide initial PA decisions within 72 hours for urgent requests (7 days for standard).
• Report PA utilization data to CMS annually (to be published publicly).

These rules increase transparency and make it easier to compare PA burden across plans.

Coverage Rules That MA Plans Cannot Change

A critical protection for MA members: MA plans cannot impose coverage criteria that are more restrictive than traditional Medicare. If traditional Medicare covers a service, the MA plan must cover it — it cannot apply internal criteria that effectively bar access to what Medicare provides.

This rule is frequently violated. When an MA plan denies skilled nursing facility care, home health, or inpatient rehabilitation using internal criteria that exceed Medicare's own standards, the denial is impermissible.

The standard for SNF coverage under Medicare is: the patient requires skilled care (skilled nursing observation and assessment, physical therapy, speech therapy, or occupational therapy) and is making progress or maintaining function. An MA plan cannot require more than this.

How to Compare Plans Before Enrolling

1. CMS Plan Finder (medicare.gov): Compare star ratings, premiums, formularies, and networks.
2. NAIC complaint ratios: Check complaint data for the specific plan entity.
3. State Health Insurance Assistance Program (SHIP): Free counseling on plan comparison in every state.
4. Annual Notice of Change: Review each year — plans can change PA requirements, premiums, and networks annually.

Fight Back With ClaimBack

Medicare Advantage denials — whether for prior authorization or post-service review — have a multi-level appeal process with meaningful reversal rates. ClaimBack helps you navigate that process.

Start your appeal at ClaimBack

Related Reading

• How to Write an Insurance Appeal Letter
• What Is Medical Necessity?
• Internal vs. External Insurance Appeals