Top 10 Reasons Claims Get Denied and How to Prevent Each One

Published April 4, 2026 · 12 min read · By RCMAXIS Revenue Cycle Team

Claim denials cost the US healthcare system an estimated $265 billion annually, according to a JAMA analysis of healthcare administrative waste. For the average medical practice, denial rates between 10-15% translate to tens of thousands in lost revenue each year. The good news: up to 90% of denials are preventable with the right processes in place.

At RCMAXIS, we maintain a 2.1% denial rate across our client base, well below the 10-15% industry average. Here is exactly how we do it, organized by the top 10 denial reasons we see across specialty practices.

1. Missing or Invalid Patient Information (Denial Code CO-4)

Incorrect patient demographics remain the single most common cause of claim denials. According to the American Medical Association (AMA), 50% of denials stem from front-end errors including missing or inaccurate data including misspelled names, wrong dates of birth, incorrect insurance ID numbers, and mismatched subscriber relationships.

Prevention Strategy

• Implement real-time eligibility verification at scheduling and check-in
• Use automated demographic verification tools integrated with your EHR system
• Train front-desk staff to verify insurance cards at every visit, not just new patients
• Cross-reference patient information against the 270/271 eligibility response before claim submission

2. Prior Authorization Not Obtained (Denial Code CO-197)

Prior authorization denials have surged 30% since 2023, according to the AMA Prior Authorization Physician Survey. Mental health services, advanced imaging, and specialty procedures are most affected. This is especially problematic for behavioral health practices where nearly every session beyond the initial evaluation may require authorization.

Prevention Strategy

• Build prior auth requirements into your scheduling workflow
• Maintain a payer-specific authorization matrix updated monthly
• Automate auth tracking with expiration alerts 7 days before deadline
• Document all authorization numbers on the claim at time of submission

3. Duplicate Claims (Denial Code CO-18)

Duplicate submissions account for approximately 14% of all denials per the Healthcare Financial Management Association (HFMA). They occur when practices resubmit claims before the original has been adjudicated, or when both the provider and billing company submit simultaneously during a billing transition.

Prevention Strategy

• Implement a 14-day hold before resubmitting any claim
• Use claim status inquiry (276/277) to check adjudication status before resubmission
• Establish clear submission ownership during billing company transitions

4. Coding Errors and Mismatches (Denial Codes CO-11, CO-97)

Incorrect CPT, ICD-10, or modifier usage causes approximately 19% of denials (AAPC 2025 Coding Benchmark Report). Common errors include diagnosis-procedure mismatches, unbundling, upcoding, and missing modifiers for bilateral procedures or distinct services.

Prevention Strategy

• Use certified coders with specialty-specific credentials (CPC, CCS, CCS-P)
• Implement pre-submission claim scrubbing with CCI edit checks
• Conduct quarterly coding audits with a minimum 10% chart sample
• Stay current with annual CPT code updates and LCD/NCD changes

5. Timely Filing Violations (Denial Code CO-29)

Each payer has different filing deadlines ranging from 90 days to 365 days from date of service. Medicare requires submission within 12 months, but many commercial payers enforce 90-day windows. MGMA data shows 7% of denials result from timely filing violations, representing entirely preventable revenue loss.

Prevention Strategy

• Submit all claims within 24-48 hours of charge entry
• Maintain a payer-specific filing deadline matrix
• Set automated alerts at 50% and 75% of each payers filing limit
• Track claim age in your analytics dashboard

6. Non-Covered Services (Denial Code CO-96)

Services deemed not medically necessary or excluded from the patients benefit plan generate roughly 8% of denials. This is prevalent in specialty clinics performing procedures that require specific diagnosis support or payer-defined frequency limits.

Prevention Strategy

• Verify coverage and benefits before scheduling procedures
• Check LCD/NCD coverage requirements against documented diagnoses
• Implement Advance Beneficiary Notices (ABNs) for Medicare patients when coverage is uncertain

7. Coordination of Benefits (COB) Issues (Denial Code CO-22)

When patients have multiple insurance plans, incorrect primary/secondary designation causes approximately 6% of denials. The birthday rule, COBRA status, and Medicare Secondary Payer rules create complexity that front-desk staff often mishandle.

Prevention Strategy

• Verify COB at every visit, not just new patient registration
• Implement automated COB detection through eligibility responses
• Train staff on the birthday rule and common COB scenarios

8. Out-of-Network Denials (Denial Code CO-151)

Network status denials have increased as payer networks narrow. According to the KFF 2025 Employer Health Benefits Survey, narrow network plans now cover 32% of insured workers, up from 23% in 2020.

Prevention Strategy

• Maintain current credentialing across all payers through proactive enrollment management
• Verify in-network status during eligibility checks, not just active coverage
• Alert patients to out-of-network status before rendering services

9. Bundling and Unbundling Errors (Denial Code CO-97)

Incorrect unbundling of services that should be billed together, or failure to append appropriate modifiers, causes significant denials in surgical and procedural specialties. Orthopedic and cardiology practices are most affected due to complex bundling rules around global periods and multiple procedure discounts.

Prevention Strategy

• Use NCCI edit checking on every claim before submission
• Ensure coders understand global surgical period rules and modifier 59/X{EPSU} usage
• Review operative reports for distinct procedural steps before adding modifier 59

10. Missing or Invalid Referral (Denial Code CO-15)

Referral-based denials particularly impact specialist practices receiving patients from primary care providers. Approximately 4% of specialty claim denials result from missing or expired referrals (MGMA).

Prevention Strategy

• Verify active referral status during scheduling
• Track referral visit counts and expiration dates in your PM system
• Request referral renewals 2 weeks before expiration

Building a Denial Prevention Program

Individual fixes are important, but systematic denial prevention requires a structured program. At RCMAXIS, our claims management approach includes root cause analysis on every denial, automated prevention workflows, and monthly denial trend reporting for each provider.

The ROI is clear: for a 10-provider practice with $5M annual revenue, reducing denials from the 12% industry average to our 2.1% rate recovers approximately $495,000 annually. That is not theoretical, it is what we deliver for our clients. See real examples in our case studies.