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CO-188 Denial Code: Covered Only Per FDA Guidance

CO-188 means the payer covers this product or procedure only when it is used according to FDA recommendations, such as approved indications, doses, or device uses. The payer believes the claim describes use outside those recommendations.

Quick facts

Code
CO-188 (CARC 188)
Status
Active In use since June 30, 2005.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The provider absorbs the denied amount. Without a valid advance notice or plan provision, it can't be billed to the patient.
  • PR (Patient Responsibility): The patient may be responsible, for example when they were informed in advance that off-label use might not be covered and agreed to pay.
Official description
This product/procedure is only covered when used according to FDA recommendations.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-188 means

CARC 188 reads “This product/procedure is only covered when used according to FDA recommendations.” The payer’s coverage for a drug, biological, device, or procedure is limited to uses consistent with FDA approval or clearance. Based on the diagnosis, dose, frequency, patient age, or device information, the payer concluded this use falls outside that.

This code is most often tied to off-label drug use, but it can also apply to devices used outside their cleared indications or equipment not FDA-approved for the service performed.

Example: a biologic is administered for a condition not listed in its labeling. The payer’s policy covers the drug only for labeled indications, and the claim is denied CO-188. The practice appeals with compendia support and documentation of prior treatment failures.

Common causes

  • Off-label indications, where the diagnosis on the claim isn’t an FDA-approved use.
  • Dose or frequency beyond labeled recommendations.
  • Patient age outside the approved population.
  • Device used outside its cleared indication, or equipment not approved for the procedure.
  • Diagnosis coding that doesn’t reflect the labeled indication the patient actually has.
  • Missing FDA or investigational device information for device trials.

How to fix it

  1. Check the payer’s policy for the drug or device to see which uses it covers.
  2. Verify coding. If the patient has a labeled indication that wasn’t coded, submit a corrected claim with resubmission code 7 in box 22 and accurate diagnoses and pointers.
  3. If the use is off-label but evidence-supported, file an appeal with compendia citations, guidelines, literature, and the clinical rationale.
  4. If the patient signed a valid advance notice, confirm the correct modifier and bill the patient per the payer’s rules.
  5. Otherwise, write off the CO amount.

How to prevent it

  • Obtain prior authorization for high-cost drugs and devices, especially for off-label use. See authorization denials.
  • Check indications against labeling and payer policy before administration.
  • Document the clinical rationale for off-label use, including prior therapies tried.
  • Use advance notices when coverage is doubtful, following each payer’s rules.
  • Code the indication accurately and link it in box 24E to the drug line.

Specialty notes

Oncology, rheumatology, and pediatrics see this code most because off-label drug use is common in those fields. Device-heavy specialties may see it when a device is used outside its cleared indication.

Remark codes that may appear with CO-188

  • M102 (Service not performed on equipment approved by the FDA for this purpose.): The service was not performed on equipment the FDA approved for this purpose.
  • MA128 (Missing/incomplete/invalid FDA approval number.): The FDA approval number is missing or invalid, often for investigational device claims.
  • N115 (This decision was based on a Local Coverage Determination (LCD).): An LCD was applied, which may specify covered indications.
  • CO-50 (These are non-covered services because this is not deemed a 'medical necessity' by the payer.): A broader medical necessity denial not tied specifically to FDA labeling.
  • CO-153 (Payer deems the information submitted does not support this dosage.): The dosage billed isn't supported, which can overlap with dosing outside labeling.
  • CO-167 (This (these) diagnosis(es) is (are) not covered.): The diagnosis isn't covered, often how off-label indications first show up.
  • CO-55 (Procedure/treatment/drug is deemed experimental/investigational by the payer.): The procedure or drug is considered experimental or investigational by the payer.

CO-188 FAQ

Does CO-188 mean off-label use is never covered?

No. Many payers cover some off-label uses when supported by recognized compendia, clinical guidelines, or peer-reviewed evidence. CO-188 means this payer applied an FDA-use requirement to this claim.

What evidence helps an appeal?

Compendia listings, published studies, specialty society guidelines, documentation of failed on-label alternatives, and the payer's own drug or device policy if it allows the use.

Can a diagnosis error cause CO-188?

Yes. If the diagnosis in box 21 doesn't reflect the approved indication the patient actually has, the use will look off-label. Correct the coding if the record supports it.