Common Procedure Code Denial Categories and Strategies to fix the AR denials
- Missing or Incorrect Modifiers (CO 4 / PR 55): One of the most common medical billing denials, where procedure codes are submitted without required modifiers to indicate laterality (RT/LT), multiple procedures (-51), or distinct services (-59). These errors directly impact medical billing AR and increase healthcare claims denials.
- Diagnosis/Procedure Mismatch (CO 11): The CPT code does not logically align with the submitted ICD-10 diagnosis, leading payers to question medical necessity—an issue frequently identified during claims denial management and targeted through AI in denial management tools.
- Global Period Bundling (CO 97): Services (such as post-op office visits) are billed separately when they are technically included in the reimbursement for a previously adjudicated procedure, resulting in avoidable medical billing denials without proper revenue cycle denial management.
- Lack of Prior Authorization (CO 15/ CO 197): Specific procedures, especially high-cost surgery or advanced imaging, are billed without the required pre-approval number in Block 23. This highlights the need for automated eligibility verification and medical billing automation.
- Inconsistent Place of Service (CO 5): The procedure code (e.g., an inpatient-only surgery) does not match the facility type (e.g., an outpatient clinic), commonly flagged in healthcare claims denials and resolved through AI medical billing workflows.
Frequently Denied CPT Codes in 2025
Service Category | High-Risk Codes | Primary Reason for AR Denial |
Arthrocentesis | 20600, 20605, 20610 | Missing laterality modifiers or bundling with other same-day procedures, increasing medical billing denials |
E/M Services | 99202–99215 | Denied as “included in procedure” if billed same-day as a surgery without Modifier 25, a major focus of AR denial management |
Telehealth | 98008–98016 | New for 2025; often rejected by Medicare or payers who haven’t updated systems—driving healthcare claims denials |
AR Follow-up Strategies for 2025
- Analyze CARCs and RARCs: Use Claim Adjustment Reason Codes (e.g., CO-16) and Remittance Advice Remark Codes (e.g., M80) to pinpoint technical errors and strengthen revenue cycle denial management.
- Verify Timely Filing: Each payer has unique deadlines; missing these triggers CO 29 and increases unresolved medical billing AR, reinforcing the need for medical billing automation.
- Correct Mismatches: If denied for CO 11, review 2025 ICD-10-CM guidelines to ensure diagnosis specificity—key for reducing medical billing denials through AI in denial management.
- Appeal with Medical Records: For CO 50 (Medical Necessity), resubmit with operative reports or clinical notes to support successful claims denial management.
Procedures that are challenging for reimbursement
In 2025, several CPT codes remain particularly challenging for reimbursement due to high improper payment rates, complex documentation requirements, and restrictive payer policies—making them prime candidates for revenue cycle management automation.
1. Evaluation and Management (E/M): CPT 99214
CPT 99214 (Level 4 established patient outpatient visit) is consistently cited as one of the most difficult codes for reimbursement and a major contributor to medical billing denials and unresolved medical billing AR.
- Improper Payment Risk: In late 2024 and throughout 2025, it topped federal lists for improper payments, generating over $564 million in errors—placing heavy pressure on AR denial management teams.
- Challenges: Approximately 63% of these denials stem from incorrect coding (upcoding), while another 20% are due to missing documentation, making it a key focus area for claims denial management and AI in denial management. Payers frequently “downcode” these to 99213 if the Medical Decision Making (MDM) or total time (30+ minutes) is not explicitly supported by the clinical notes.
2.Telemedicine: New 2025 Codes (98000–98015)
The 2025 transition to new telemedicine codes has created immediate AR challenges and increased healthcare claims denials, highlighting gaps in medical billing automation.
- Reimbursement Gaps: Although the CPT set introduced 17 new codes for virtual visits, Medicare does not recognize 16 of them for separate reimbursement as of early 2025, increasing medical billing denials.
- Complexity: Codes 98000–98015 (replacing telephone codes 99441–99443) require specific modes of communication (audio-video vs. audio-only) and strict time thresholds, driving the need for AI medical billing and revenue cycle denial management.
3. Emerging Technology: Category III (T-Codes)
Category III codes (e.g., 0877T–0940T) represent new technologies like AI-augmented imaging and continuous ECG monitoring and are among the most challenging areas for claims denial management.
- Payer Scrutiny: These are notoriously difficult to get reimbursed because many payers consider them “experimental” or “investigational”, resulting in high medical billing denials.
- Administrative Burden: Success often requires submitting extensive clinical evidence or individual Letters of Medical Necessity, making denial management automation and AI in denial management essential.
4. Chronic Care Management (CCM): 99490 & 99491
While vital for revenue, CCM codes face intense scrutiny in 2025 and are a frequent source of medical billing AR delays.
- Time Tracking: Rejections often occur because the required clinical staff time (20 minutes for 99490) or physician time (30 minutes for 99491) is not precisely documented, increasing healthcare claims denials.
- Audit Risk: These codes have a high rate of CO-151 denials, reinforcing the need for medical billing automation, claims denial management, and revenue cycle management automation.
5. Summary of Top AR Denial Reasons (2025)
Denial Code | Primary Trigger | Challenging Code Types |
CO-11 | Coding Mismatch | Mismatched ICD-10 to CPT |
CO-50 | Medical Necessity | Advanced Diagnostics, T-Codes |
CO-97 | Bundled Service | Minor procedures (like 20600) billed with E/M |
CO-15 | Prior Authorization | High-cost imaging or surgeries |
6. Musculoskeletal & Minor Procedures (e.g., CPT 20600)
Minor procedures are frequently denied when they are bundled into an office visit on the same day without a distinct anatomical diagnosis, significantly impacting medical billing AR and AR denial management.
Challenging CPT | Typical ICD-10 Requirement | Common Denial Reason (2025) |
20600 (Small joint injection) | M25.511 (Pain in right finger) | CO-4: Missing laterality modifier (RT/LT), leading to medical billing denials |
20610 (Major joint injection) | M17.11 (Unilateral osteoarthritis, right knee) | CO-97: Denied as “included in another service” if billed with an E/M visit without Modifier 25. |
20552 / 20553 (Trigger point injections) | M79.1 (Myalgia) | CO-11: Mismatch; many payers require specific anatomical location codes rather than general “muscle pain”. |
7. New 2025 CPT Codes with High Rejection Rates
Codes introduced in the 2025 CPT Update often face “experimental” or “non-covered” increased healthcare claims denials as payer systems update.
New 2025 CPT | Category | Rejection Reason |
98000–98016 | Telemedicine | CO-167: Non-covered; Medicare currently does not recognize these for separate payment, preferring existing office-based codes with modifiers. |
G0556–G0558 | Advanced Primary Care Management | CO-B15: Requires “qualifying service”; these may be denied if billed concurrently with other care management codes like 99490. |
64466–64474 | Fascial Plane Blocks | CO-15: Missing prior authorization; payers frequently require pre-approval for these new pain management techniques. |
8. Diagnostic & Laboratory HCPCS Rejections
Supplies and drug injections (HCPCS) often fail due to missing units or non-specific diagnosis codes, increasing medical billing denials.
- J-Codes (Injectable Drugs): Codes like J0163 (Epinephrine) or J3290 (Tranexamic acid) are rejected if the number of units billed does not match the dosage recorded affecting medical billing AR.
- Preventive Screenings: G0444 (Depression screening) requires 89 (Encounter for screening for other disorders). Using a symptom code (like R45.89) instead of a screening code triggers a CO-11 denial under claims denial management review.
- DME (Durable Medical Equipment): Codes like E0658 (Segmental pneumatic appliance) are often denied for CO-16 (incomplete info) if the specific manufacturer and model details are missing reinforcing the importance of denial management automation.
