Introduction
Medical claim denials represent a significant challenge for internal medicine practices nationwide. With denial rates often reaching 10-15% of submitted claims, these rejections directly impact both revenue cycles and patient satisfaction. For internal medicine physicians focusing on complex chronic conditions and preventive care, understanding the most common denial reasons is crucial for financial stability. This blog explores the top 10 denial codes that internal medicine practices encounter, offering practical prevention strategies to optimize reimbursement processes and reduce administrative burden.
Common Denial Codes in Internal Medicine
Below is a table outlining the top 10 denial codes that internal medicine practices commonly encounter:
| Denial Code | Description |
|---|---|
CO-50 | Non-covered services / not medically necessary |
CO-16 | Missing/incorrect info or submission errors |
CO-18 | Duplicate claim/service |
CO-96 | Non-covered charges |
CO-197 | Prior authorization or precertification required |
CO-29 | Timely filing |
CO-119 | Benefit maximum reached |
CO-22 | Coordination of benefits (COB) issues |
CO-109 | Service not covered by this payer |
CO-45 | Charges exceed fee schedule/allowance |
Detailed Analysis of Top 10 Denials
1. Denial Code: CO-50
Description: Medical Necessity Denials
Medical necessity denials occur when payers determine that services provided don’t meet their criteria for being medically required. As the most common denial in internal medicine, CO-50 denials frequently affect diagnostic testing, extended evaluation and management (E&M) visits, and certain treatments that insurers deem unnecessary or excessive for the documented condition.
Prevention:
- Document clear clinical reasoning that connects symptoms, findings, and diagnostic or treatment decisions
- Ensure diagnoses are specific (use the highest level of specificity in ICD-10 coding)
- Support medical necessity with comprehensive assessment notes that demonstrate clinical decision-making
- Stay current with payer-specific medical policies and coverage determinations
- Implement pre-service verification processes for commonly denied services
- Develop templates that prompt physicians to document elements that support medical necessity
2. Denial Code: CO-16
Description: Missing or Invalid Information
The CO-16 denial indicates that a claim lacks essential information or contains errors preventing proper processing. Common issues include missing patient demographics, incorrect insurance information, invalid diagnosis codes, or missing referring physician information. In internal medicine practices with complex patient cases, comprehensive documentation is especially critical.
Prevention:
- Implement front-end verification systems to catch missing fields before submission
- Create mandatory fields in your EHR/practice management system
- Establish pre-submission claim scrubbing protocols
- Conduct regular staff training on payer-specific requirements
- Perform weekly audits on denied claims to identify recurring documentation gaps
- Implement automated eligibility verification at every patient encounter
3. Denial Code: CO-18
Description: Duplicate Claim Submission
Duplicate claim denials occur when the same service is billed multiple times, whether inadvertently or due to resubmission without proper modification. These denials often occur when practices resubmit claims that appear unpaid without first verifying their status or when multiple staff members process the same encounter.
Prevention:
- Implement claim tracking systems to monitor submission status
- Establish clear protocols for claim follow-up and resubmission
- Use practice management software with duplicate detection capabilities
- Train staff to verify claim status before resubmission
- Implement unique identifier tracking for all submitted claims
- Centralize the billing process to avoid multiple staff submitting the same claims
4. Denial Code: CO-96
Description: Non-Covered Charges
The CO-96 denial applies to services explicitly excluded from coverage under the patient’s insurance plan. For internal medicine practices, these often include certain preventive screenings outside recommended intervals, experimental treatments, or lifestyle interventions not typically covered by traditional plans.
Prevention:
- Maintain updated databases of payer-specific coverage policies
- Verify coverage for uncommon services before performing them
- Obtain Advanced Beneficiary Notices (ABNs) or similar waivers when appropriate
- Educate patients about potentially non-covered services before delivery
- Develop financial counseling protocols for services with variable coverage
- Create a reference guide of commonly non-covered services by payer for staff
5. Denial Code: CO-197
Description: Prior Authorization Required
This denial indicates that the service required prior authorization that was either not obtained or not properly documented. In internal medicine, these denials frequently affect advanced imaging studies, specialty referrals, certain medications, and procedures performed in the office setting.
Prevention:
- Implement a robust prior authorization tracking system
- Develop a service-specific checklist of procedures requiring authorization by payer
- Cross-train multiple staff members on authorization procedures
- Document authorization numbers in both the practice management system and patient record
- Verify authorization status before providing services
- Create a calendar system for tracking authorization expiration dates
6. Denial Code: CO-29
Description: Timely Filing
Timely filing denials occur when claims are submitted after the payer’s deadline for claim submission has passed. These deadlines vary significantly among payers, ranging from 30 days to over a year from the date of service, creating a complex compliance challenge for internal medicine practices.
Prevention:
- Maintain a comprehensive database of payer-specific filing deadlines
- Establish weekly claim submission protocols rather than batching claims monthly
- Implement aging reports to identify unbilled services approaching deadlines
- Create escalation protocols for claims nearing filing limits
- Establish claim tracking systems that flag approaching deadlines
- Develop specific procedures for handling retroactive eligibility situations
7. Denial Code: CO-119
Description: Benefit Maximum Reached
The CO-119 code indicates that the patient has reached the maximum benefit allowed under their insurance plan for a particular service or time period. This commonly affects preventive services, therapy visits, or certain chronic disease management services in internal medicine practice.
Prevention:
- Verify benefits and limitations before providing services
- Track utilization of services with known limits throughout the benefit period
- Implement an alert system for patients approaching benefit limitations
- Provide clear financial counseling for patients nearing benefit maximums
- Train scheduling staff to verify remaining benefits before booking appointments
- Develop alternative care plans for patients who have reached coverage limits
8. Denial Code: CO-22
Description: Coordination of Benefits Issues
COB denials occur when a patient has multiple insurance policies and claims are not processed in the correct order of benefits. Internal medicine patients, particularly those with Medicare plus secondary coverage or those covered under multiple family policies, frequently trigger these denials.
Prevention:
- Verify primary and secondary coverage at each patient visit
- Document detailed insurance information including policy numbers, group numbers, and effective dates
- Implement systematic insurance card scanning at check-in
- Follow up promptly on COB denials to determine correct billing order
- Train front desk staff to ask specific questions about multiple coverage situations
9. Denial Code: CO-109
Description: Service Not Covered by This Payer
This denial indicates that the service is not covered by the specific insurance plan to which the claim was submitted. This often occurs when practices submit claims to the wrong insurance carrier or when patients have recently changed coverage without notifying the practice.
Prevention:
- Verify insurance eligibility at every patient encounter
- Implement real-time eligibility verification systems
- Create protocols for confirming current insurance information at each visit
- Maintain updated records of payer mergers and plan changes
- Train staff to recognize signs of potential coverage changes
- Develop patient education materials emphasizing the importance of providing updated insurance information
10. Denial Code: CO-45
Description: Charges Exceed Fee Schedule
The CO-45 denial occurs when the amount billed exceeds the payer’s allowed amount for the service. While not technically a full denial, these adjustments can significantly impact reimbursement when practices are unfamiliar with contracted fee schedules or when billing non-contracted services.
Prevention:
- Maintain current fee schedules for major payers
- Regularly review explanation of benefits (EOBs) to identify reimbursement patterns
- Update charge masters based on payer-specific allowable amounts
- Monitor for unexpected reductions in reimbursement rates
- Consider contract negotiations when reimbursement rates consistently fall below regional averages
- Implement claim scrubbing tools that flag charges exceeding typical allowable amounts
Conclusion
Understanding and addressing these top ten denial reasons can significantly improve the revenue cycle performance of internal medicine practices. The most effective denial management strategy combines proactive prevention with efficient resolution processes. By investing in staff training, implementing robust verification systems, and developing payer-specific protocols, internal medicine practices can reduce denial rates and accelerate reimbursement.
Remember that denial management is not a one-time project but an ongoing process requiring regular monitoring and adjustment. By tracking denial patterns, measuring improvement, and continuously refining prevention strategies, internal medicine practices can transform denial management from a reactive burden into a strategic advantage that supports both financial success and quality patient care.