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CO-107 Denial Code: Qualifying Service Not Identified

CO-107 means the payer could not find the related or qualifying claim or service that this service depends on. The classic example is an add-on code billed without its primary procedure, or a service that is payable only when linked to another claim.

Quick facts

Code
CO-107 (CARC 107)
Status
Active In use since January 1, 1995; last modified July 1, 2017.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The provider is responsible for identifying the qualifying service. The amount is not billable to the patient and is typically fixed through correction or rebilling.
Official description
The related or qualifying claim/service was not identified on this claim. Usage: Refer to the 835 Healthcare Policy Identification Segment (loop 2110 Service Payment Information REF), if present.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-107 means

CARC 107 says the related or qualifying claim/service was not identified on this claim. Some services are payable only when another service is also present. When the payer cannot find that qualifying service on the claim or in its history, it denies the dependent line with CARC 107. The payer may cite a specific policy in the 835 policy segment (loop 2110 REF).

The textbook case is an add-on code. Add-on codes describe additional work performed alongside a primary procedure and cannot be paid alone. If the primary is missing, denied, or on a claim the payer cannot link, the add-on is denied.

Example: a claim includes an add-on for additional time or units, but the primary procedure line was accidentally left off. The payer denies the add-on with CO-107 and remark N122.

Common causes

  • An add-on code billed without its primary code on the same claim and date.
  • The primary procedure was denied, so the add-on lost its qualifying service.
  • Primary and add-on services split across two claims submitted at different times.
  • Different dates of service on the primary and add-on lines because of a data entry error.
  • A service that requires a prior qualifying visit or procedure, such as follow-up care, billed before the qualifying claim was processed.
  • The primary was billed under a different rendering provider (box 24J) than the add-on, when the payer expects a match.

How to fix it

  1. Find the qualifying service. Use the remark code and the payer’s policy to identify what the line depends on.
  2. If the primary was left off, send a corrected claim (resubmission code 7 in box 22) that includes both lines on the same date.
  3. If the primary was denied, resolve that denial first. Once it is paid, request reprocessing of the add-on or resubmit per the payer’s instructions.
  4. If the qualifying service was on a separate claim, ask the payer whether it will link the claims on reprocessing, or rebill them together.
  5. If both were billed correctly, file a reconsideration and point to the claim and line of the qualifying service.

How to prevent it

  • Scrub claims for add-on codes without an eligible primary on the same date. A Claims Validator can catch this before submission.
  • Keep primary and add-on services on the same claim with the same rendering provider and date.
  • Hold dependent services until the qualifying claim is submitted.
  • For more on edits that pair procedures, see NCCI denials, PTP bundling, and modifiers.

Specialty notes

Behavioral health practices often bill psychotherapy add-ons alongside a separately documented E/M service. If the E/M line is denied or missing, the add-on can deny with CO-107, so fix the E/M first.

Remark codes that may appear with CO-107

  • N122 (Add-on code cannot be billed by itself.): Add-on code billed by itself, the most common trigger for this denial.
  • N674 (Not covered unless a pre-requisite procedure/service has been provided.): Not covered unless a prerequisite procedure or service has been provided.
  • CO-B15 (This service/procedure requires that a qualifying service/procedure be received and covered.): Very close in meaning: the service requires a qualifying service that was not received or was not paid.
  • CO-97 (The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.): The opposite problem: the service was paid as part of another service.
  • CO-16 (Claim/service lacks information or has submission/billing error(s).): General missing information, sometimes used instead when linking data is absent.
  • OA-18 (Exact duplicate claim/service (Use only with Group Code OA except where state workers' compensation regulations requires CO)): Duplicate claim, which can happen if the primary and add-on are split and resubmitted carelessly.

CO-107 FAQ

What does qualifying service mean in CO-107?

A service that must also be billed, or already paid, for this service to be payable. Add-on codes need their primary code; some follow-up services need the original procedure on file.

Should I appeal CO-107?

Usually not first. Most CO-107 denials are fixed by correcting the claim so the qualifying service is present or referenced. Appeal only if the qualifying service was clearly on the claim or already paid.

Can the primary and add-on be billed by different providers?

Payer rules vary. Generally the add-on is billed by the same provider who performed the primary service on the same date. Check the payer's policy when they differ.