# CARC 50 Denial Code (Non-Covered Services Not Deemed Medically Necessary) | ANSI 835 EDI Spec
> Comprehensive healthcare EDI technical reference and denial resolution guide for Claim Adjustment Reason Code 50 (Non-Covered Services Not Deemed Medically Necessary) under ANSI ASC X12 835 005010X221A1.

- **Canonical URL:** https://stanzaapi.com/tools/x12-parser/carc/carc-50-not-medically-necessary
- **Governing Standard:** ANSI ASC X12 Standards (005010) (Accredited Standards Committee X12 / HIPAA 5010)
- **Edge Latency SLA:** <2ms Edge (Cloudflare V8 Isolates)
- **Execution Model:** Pure compute $f(x) = y$, 100% In-Memory (Zero Store, Zero Log)

## Technical Overview & Governing Rules
Claim Adjustment Reason Code (CARC) 50 communicates: "These are non-covered services because this is not deemed a "medical necessity" by the payer.".

In ANSI X12 835 Electronic Remittance Advice (ERA) files, CARC 50 is reported in Loop 2110 (Service Payment Information) or Loop 2100 (Claim Payment Information) under the Claim Adjustment (CAS) segment with Group Code 'CO' (Contractual Obligation), formatted as: CAS*CO*50*AMOUNT~.

Root Cause: Payer’s medical review or automated Local Coverage Determination (LCD) policy concluded clinical documentation did not support medical necessity for procedure code.

Adjudication & Appeal Strategy: File level-one redetermination appeal with physician clinical chart notes, operative report, and literature supporting medical necessity.

## Specification Matrix
| Attribute | Value | Technical Guidance |
| --- | --- | --- |
| Reason Code | CARC 50 | Non-Covered Services Not Deemed Medically Necessary |
| Standard Group Code | CO | Contractual Obligation |
| ANSI 835 Segment | CAS*CO*50*AMOUNT~ | Loop 2110 or Loop 2100 |
| Balance Billing Patient | Prohibited unless patient executed valid ABN prior to encounter. | Compliance with billing regulations |
| Common RARCs | N115, M38 | Remittance Advice Remark Codes |
| Recommended Action | File level-one redetermination appeal with physician clinical chart notes, operative report, and literature supporting medical necessity. | Workflow for billing teams |

## Standard JSON Response Model
```json
{
  "transactionType": "835",
  "claimNumber": "CLM-2026-001",
  "adjudication": {
    "billedAmount": 500,
    "paidAmount": 0,
    "adjustments": [
      {
        "groupCode": "CO",
        "groupName": "Contractual Obligation",
        "reasonCode": "50",
        "reasonDescription": "Non-Covered Services Not Deemed Medically Necessary",
        "adjustmentAmount": 500
      }
    ]
  }
}
```

## Frequently Asked Questions & Edge Cases
### Q: What does CARC 50 mean on an 835 ERA?
**A:** CARC 50 signifies: "These are non-covered services because this is not deemed a "medical necessity" by the payer.". It explains why the payer did not pay the full billed charge.

### Q: Can a provider balance-bill the patient for CARC 50?
**A:** Prohibited unless patient executed valid ABN prior to encounter.

### Q: How do medical billing teams resolve and appeal CARC 50?
**A:** File level-one redetermination appeal with physician clinical chart notes, operative report, and literature supporting medical necessity.