Why Are My Medicare Claims Being Denied?
Medicare claims are typically denied when a service is deemed not medically necessary under National or Local Coverage Determinations (NCDs/LCDs), contains coding or modifier mismatches, lacks required clinical documentation, fails to meet prior authorization rules (especially under Medicare Advantage), or exceeds Medicare’s 12-month timely filing window.
Understanding whether a denial is a soft denial (correctable technical error) or a hard denial (medical necessity or coverage policy rejection) is essential for rapid resubmission and recovering lost revenue.
At The Medicator’s, our revenue cycle experts perform automated claim scrubbing, analyze remittance advice remark codes (RARCs), and rapidly file formal appeals to recover unpaid revenue. Practices seeking to eliminate billing backlogs and protect practice cash flow benefit directly from partnering with an established provider of internal medicine billing services in Texas and nationwide.
Primary Causes of Medicare Claim Denials
Lack of Medical Necessity (CARC CO-50 / CO-151): The billed CPT® code is not supported by a qualifying ICD-10 diagnosis code mandated by CMS or local coverage guidelines.
Billing & Coding Inaccuracies (CARC CO-16): Invalid or deleted ICD-10/CPT codes, missing specificity, unbundled service codes (NCCI edits), or missing mandatory modifiers (such as Modifier 25 or 59).
Missing Clinical Documentation: Operational failure to attach chart notes, physician signatures, or lab/diagnostic proof to electronic claim submissions.
Missing Prior Authorization (CARC CO-197): Performing advanced imaging, complex procedures, or specialty care without pre-approval—a major driver of denials in Medicare Advantage plans.
Timely Filing Expiration (CARC CO-29): Submitting original claims beyond Medicare’s strict 12-month calendar deadline from the date of service.
Coordination of Benefits / Secondary Payer (CARC CO-22): Failing to bill a primary commercial plan or worker’s compensation insurer before routing the claim to Medicare as secondary.
Top Medicare Claim Adjustment Reason Codes (CARCs)
Understanding standard denial codes on your Explanation of Benefits (EOB) or Electronic Remittance Advice (ERA) accelerates claim resolution:
| Denial Code (CARC) | Description | Root Cause | Primary Fix |
| CO-16 | Incomplete or missing information | Missing NPI, taxonomy, patient demographic error, or unattached chart notes. | Correct technical data and resubmit as a corrected claim. |
| CO-50 / CO-151 | Service not deemed medically necessary | Diagnosis code does not satisfy LCD/NCD coverage criteria. | Update to a specific supporting ICD-10 code or submit clinical appeal notes. |
| CO-97 | Procedure bundled into another service | National Correct Coding Initiative (NCCI) PTP editing violation. | Check NCCI edits; append Modifier 25 or 59 if services were distinct and documented. |
| CO-197 | Pre-authorization / Pre-certification missing | Authorization not requested prior to procedure execution. | Request retro-authorization or appeal with urgent medical necessity proof. |
| CO-29 | Timely filing limit exceeded | Claim submitted after 12 months from the date of service. | Provide clearinghouse submission proof showing initial receipt within timeframe. |
The 5-Level Medicare Appeals Process
When a claim is denied due to medical necessity or policy non-coverage, healthcare practices can appeal through Medicare’s structured multi-level process:
1. Level 1: Redetermination by the MAC
Submit a formal Redetermination request to your regional Medicare Administrative Contractor (MAC) within 120 days of receiving the initial denial notification. Include complete medical records, practitioner notes, and physician attestations.
2. Level 2: Reconsideration by a QIC
If Level 1 is unfavorable, file for Reconsideration through an independent Qualified Independent Contractor (QIC) within 180 days. Reconsiderations require detailed clinical documentation proving medical necessity.
3. Level 3: Hearing by an Administrative Law Judge (ALJ)
If the claim exceeds the annual statutory amount in controversy threshold, appeal for an ALJ hearing within 60 days of the QIC decision.
4. Level 4: Medicare Appeals Council Review
If the ALJ decision is unfavorable, request a review by the Medicare Appeals Council within 60 days.
5. Level 5: Judicial Review in Federal District Court
For high-dollar claims meeting statutory thresholds, file an action in U.S. District Court within 60 days of the Appeals Council decision.
Strategic Action Plan to Prevent Medicare Denials
Conduct Real-Time Front-Desk Verification: Verify active Medicare Part B eligibility and Medicare Advantage enrollment before every scheduled encounter.
Automate Clearinghouse Claim Scrubbing: Program pre-submission edits to check NCCI bundling rules, modifier application, and active ICD-10 sets.
Monitor LCD & NCD Coverage Policies: Stay updated on regional MAC coverage requirements to ensure ordered tests match covered diagnosis codes.
Action Remittances Within 48 Hours: Establish immediate workflows to fix and resubmit soft denials (CO-16) within two business days to keep cash flowing.
Eliminate Claim Denials with The Medicator’s
Unresolved Medicare denials slow cash flow, increase administrative overhead, and risk total revenue loss. At The Medicator’s, our certified revenue cycle management team identifies denial root causes, handles complex Medicare appeals, and maintains clean claim rates above 97%.
Ready to recover lost revenue and prevent future Medicare claim rejections? Request a free, custom practice analysis with The Medicator’s today to audit your practice denial trends and secure your practice revenue!
