Latency: <2ms Edge Availability: 99.99% Standard: ANSI 835 / WPC CARC Verified: Sep 2026 V8 Pure Compute

CARC 4 Denial Code (Procedure Code Inconsistent with Modifier Used) | ANSI 835 EDI Spec

Q: What does CARC 4 mean on an 835 ERA?

CARC 4 signifies: "The procedure code is inconsistent with the modifier used or a required modifier is missing.". It explains why the payer did not pay the full billed charge.

Q: How do medical billing teams resolve and appeal CARC 4?

Review CPT modifier rules, remove invalid modifier or append missing anatomical/informational modifier, and submit corrected claim.

Comprehensive healthcare EDI technical reference and denial resolution guide for Claim Adjustment Reason Code 4 (Procedure Code Inconsistent with Modifier Used) under ANSI ASC X12 835 005010X221A1.

View Pricing & SLA → ⚡ Test in Live Workbench ← Back to Healthcare EDI ANSI X12 Parser API

Official Regulatory Standard & Verification Protocol Authority: Accredited Standards Committee X12 / HIPAA 5010 ↗

Direct Answer Capsule: Comprehensive healthcare EDI technical reference and denial resolution guide for Claim Adjustment Reason Code 4 (Procedure Code Inconsistent with Modifier Used) under ANSI ASC X12 835 005010X221A1. Conforms strictly to ANSI ASC X12 Standards (005010) with zero cold-starts and deterministic edge verification.

Execution SLA

<2ms Edge (Cloudflare V8)

Governing Norm

ANSI 835 / WPC CARC

Active Standard

Sep 2026 Edition

Throughput Limit

512 KB / Payload

Data Privacy

100% In-Memory (Zero Store)

Interactive Edge Workbench

⚡ Live CARC 4 Denial Code (Procedure Code Inconsistent with Modifier Used) | ANSI 835 EDI Spec Interactive Workbench

Test real-time validation and deterministic schema parsing for CARC 4 Denial Code (Procedure Code Inconsistent with Modifier Used) | ANSI 835 EDI Spec directly in your browser. Sub-5ms Cloudflare edge execution with zero setup.

32KB Demo Cap 60 req/min Burst <2ms V8 Compute Zero Data Retention

input.x12 0 B

output.json demo-ready

Status: Ready

{
  "status": "Click 'Run Edge Parse' to test live on Global Edge Isolates..."
}

Specification & Structural Breakdown

Technical Rule Summary: Implementation conforms strictly to ANSI ASC X12 Standards (005010). Data ingestion is fully deterministic: identical inputs always produce bit-for-bit identical outputs without ambient side-effects.

Claim Adjustment Reason Code (CARC) 4 communicates: "The procedure code is inconsistent with the modifier used or a required modifier is missing.".

In ANSI X12 835 Electronic Remittance Advice (ERA) files, CARC 4 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*4*AMOUNT~.

Root Cause: Incompatible CPT/HCPCS modifier (e.g., billing bilateral modifier 50 on a code that already includes bilateral services, or missing modifier 25 on E/M with procedure).

Adjudication & Appeal Strategy: Review CPT modifier rules, remove invalid modifier or append missing anatomical/informational modifier, and submit corrected claim.

Attribute	Value	Technical Guidance
Reason Code	CARC 4	Procedure Code Inconsistent with Modifier Used
Standard Group Code	CO	Contractual Obligation
ANSI 835 Segment	CASCO4*AMOUNT~	Loop 2110 or Loop 2100
Balance Billing Patient	Prohibited.	Compliance with billing regulations
Common RARCs	M20, N519	Remittance Advice Remark Codes
Recommended Action	Review CPT modifier rules, remove invalid modifier or append missing anatomical/informational modifier, and submit corrected claim.	Workflow for billing teams

Parsed JSON Response Model

The edge microservice transforms input payloads into strongly-typed hierarchical JSON envelopes with sub-5ms latency:

HTTP 200 JSON Response Envelope

{
  "transactionType": "835",
  "claimNumber": "CLM-2026-001",
  "adjudication": {
    "billedAmount": 500,
    "paidAmount": 0,
    "adjustments": [
      {
        "groupCode": "CO",
        "groupName": "Contractual Obligation",
        "reasonCode": "4",
        "reasonDescription": "Procedure Code Inconsistent with Modifier Used",
        "adjustmentAmount": 500
      }
    ]
  }
}

Copy-Paste Integration Code (5 Languages)

Integrate CARC 4 Denial Code (Procedure Code Inconsistent with Modifier Used) | ANSI 835 EDI Spec directly into your production application with native, zero-dependency code snippets in cURL, Node.js, Python, Go, and C#:

curl --request POST \
  --url "https://healthcare-edi-ansi-x12-parser-837p-835-271.stanzaapi.com/api/v1/x12/parse" \
  --header "Content-Type: application/json" \
  --header "x-api-key: YOUR_API_KEY" \
  --data '{
  "raw": "ISA*00*          *00*          *ZZ*SUBMITTER1     *ZZ*RECEIVER01     *260830*1200*^*00501*000000001*0*P*:~GS*HC*SENDER*RECEIVER*20260830*1200*1*X*005010X222A1~ST*837*0001*005010X222A1~BHT*0019*00*CLAIM001*20260830*1200*CH~NM1*41*2*DR DOE CLINIC*****46*1234567890~PER*IC*SUPPORT*TE*8005551212~HL*1**20*1~NM1*85*2*DR DOE CLINIC*****XX*1992837465~HL*2*1*22*0~NM1*IL*1*SMITH*JANE****MI*W123456780~CLM*CLM001*150.00***11::1*Y*A*Y*Y~LX*1~SV1*HC:99213*150.00*UN*1***1~SE*11*0001~GE*1*1~IEA*1*000000001~"
}'

const response = await fetch("https://healthcare-edi-ansi-x12-parser-837p-835-271.stanzaapi.com/api/v1/x12/parse", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "x-api-key": process.env.API_KEY || "YOUR_API_KEY"
  },
  body: JSON.stringify({
  "raw": "ISA*00*          *00*          *ZZ*SUBMITTER1     *ZZ*RECEIVER01     *260830*1200*^*00501*000000001*0*P*:~GS*HC*SENDER*RECEIVER*20260830*1200*1*X*005010X222A1~ST*837*0001*005010X222A1~BHT*0019*00*CLAIM001*20260830*1200*CH~NM1*41*2*DR DOE CLINIC*****46*1234567890~PER*IC*SUPPORT*TE*8005551212~HL*1**20*1~NM1*85*2*DR DOE CLINIC*****XX*1992837465~HL*2*1*22*0~NM1*IL*1*SMITH*JANE****MI*W123456780~CLM*CLM001*150.00***11::1*Y*A*Y*Y~LX*1~SV1*HC:99213*150.00*UN*1***1~SE*11*0001~GE*1*1~IEA*1*000000001~"
})
});

const data = await response.json();
console.log(data);

import requests
import json

url = "https://healthcare-edi-ansi-x12-parser-837p-835-271.stanzaapi.com/api/v1/x12/parse"
headers = {
    "Content-Type": "application/json",
    "x-api-key": "YOUR_API_KEY"
}
payload = {
    "raw": "ISA*00*          *00*          *ZZ*SUBMITTER1     *ZZ*RECEIVER01     *260830*1200*^*00501*000000001*0*P*:~GS*HC*SENDER*RECEIVER*20260830*1200*1*X*005010X222A1~ST*837*0001*005010X222A1~BHT*0019*00*CLAIM001*20260830*1200*CH~NM1*41*2*DR DOE CLINIC*****46*1234567890~PER*IC*SUPPORT*TE*8005551212~HL*1**20*1~NM1*85*2*DR DOE CLINIC*****XX*1992837465~HL*2*1*22*0~NM1*IL*1*SMITH*JANE****MI*W123456780~CLM*CLM001*150.00***11::1*Y*A*Y*Y~LX*1~SV1*HC:99213*150.00*UN*1***1~SE*11*0001~GE*1*1~IEA*1*000000001~"
}

response = requests.post(url, json=payload, headers=headers)
print(response.json())

package main

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"os"
)

func main() {
	url := "https://healthcare-edi-ansi-x12-parser-837p-835-271.stanzaapi.com/api/v1/x12/parse"
	payload := []byte(`{"raw":"ISA*00*          *00*          *ZZ*SUBMITTER1     *ZZ*RECEIVER01     *260830*1200*^*00501*000000001*0*P*:~GS*HC*SENDER*RECEIVER*20260830*1200*1*X*005010X222A1~ST*837*0001*005010X222A1~BHT*0019*00*CLAIM001*20260830*1200*CH~NM1*41*2*DR DOE CLINIC*****46*1234567890~PER*IC*SUPPORT*TE*8005551212~HL*1**20*1~NM1*85*2*DR DOE CLINIC*****XX*1992837465~HL*2*1*22*0~NM1*IL*1*SMITH*JANE****MI*W123456780~CLM*CLM001*150.00***11::1*Y*A*Y*Y~LX*1~SV1*HC:99213*150.00*UN*1***1~SE*11*0001~GE*1*1~IEA*1*000000001~"}`)

	req, _ := http.NewRequest("POST", url, bytes.NewBuffer(payload))
	req.Header.Add("Content-Type", "application/json")
	req.Header.Add("x-api-key", os.Getenv("API_KEY"))

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)
	fmt.Println(string(body))
}

using System;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        using var client = new HttpClient();
        client.DefaultRequestHeaders.Add("x-api-key", Environment.GetEnvironmentVariable("API_KEY") ?? "YOUR_API_KEY");

        var json = @"{""raw"":""ISA*00*          *00*          *ZZ*SUBMITTER1     *ZZ*RECEIVER01     *260830*1200*^*00501*000000001*0*P*:~GS*HC*SENDER*RECEIVER*20260830*1200*1*X*005010X222A1~ST*837*0001*005010X222A1~BHT*0019*00*CLAIM001*20260830*1200*CH~NM1*41*2*DR DOE CLINIC*****46*1234567890~PER*IC*SUPPORT*TE*8005551212~HL*1**20*1~NM1*85*2*DR DOE CLINIC*****XX*1992837465~HL*2*1*22*0~NM1*IL*1*SMITH*JANE****MI*W123456780~CLM*CLM001*150.00***11::1*Y*A*Y*Y~LX*1~SV1*HC:99213*150.00*UN*1***1~SE*11*0001~GE*1*1~IEA*1*000000001~""}";
        var payload = new StringContent(json, Encoding.UTF8, "application/json");

        var response = await client.PostAsync("https://healthcare-edi-ansi-x12-parser-837p-835-271.stanzaapi.com/api/v1/x12/parse", payload);
        var content = await response.Content.ReadAsStringAsync();
        Console.WriteLine(content);
    }
}

Frequently Asked Questions & Technical Notes

What does CARC 4 mean on an 835 ERA?

CARC 4 signifies: "The procedure code is inconsistent with the modifier used or a required modifier is missing.". It explains why the payer did not pay the full billed charge.

Can a provider balance-bill the patient for CARC 4?

Prohibited.

How do medical billing teams resolve and appeal CARC 4?

Review CPT modifier rules, remove invalid modifier or append missing anatomical/informational modifier, and submit corrected claim.

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CARC 4 Denial Code (Procedure Code Inconsistent with Modifier Used) | ANSI 835 EDI Spec

⚡ Live CARC 4 Denial Code (Procedure Code Inconsistent with Modifier Used) | ANSI 835 EDI Spec Interactive Workbench

Specification & Structural Breakdown

Parsed JSON Response Model

Copy-Paste Integration Code (5 Languages)

Frequently Asked Questions & Technical Notes

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