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CO-194 Denial Code: Anesthesia by Surgeon or Attending

CO-194 means anesthesia was performed by the operating physician, assistant surgeon, or attending physician, so the payer won't pay it as a separate anesthesia service. Anesthesia by the surgeon is generally considered part of the surgical payment.

Quick facts

Code
CO-194 (CARC 194)
Status
Active In use since February 28, 2006; last modified September 30, 2007.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The provider absorbs the amount. The patient isn't responsible for anesthesia that the payer considers included in surgery.
Official description
Anesthesia performed by the operating physician, the assistant surgeon or the attending physician.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-194 means

CARC 194 reads “Anesthesia performed by the operating physician, the assistant surgeon or the attending physician.” Payers generally pay separately for anesthesia only when it’s provided by someone other than the physicians performing or attending the procedure, such as an anesthesiologist or CRNA. When the anesthesia claim shows the surgeon, assistant, or attending as the provider, the payer considers it included in the surgical fee.

Example: a surgeon performs a procedure and administers a regional block personally. The practice bills an anesthesia service under the surgeon’s NPI. The payer denies it with CO-194, since the block is considered part of the surgical service when the surgeon provides it.

Common causes

  • Anesthesia billed under the surgeon’s NPI, whether by design or because of a default rendering provider.
  • Assistant surgeon listed as the anesthesia provider.
  • Wrong rendering NPI in box 24J when a separate anesthesia provider actually performed it.
  • Misunderstanding of sedation rules, billing anesthesia codes instead of the codes that apply when the proceduralist provides sedation.
  • Payer policy that doesn’t pay for surgeon-administered blocks separately.

How to fix it

  1. Confirm who provided anesthesia from the anesthesia record and operative note.
  2. If a separate anesthesia provider did it, submit a corrected claim (resubmission code 7) with that provider’s rendering NPI, the anesthesia modifiers (such as AA or QK or QX, as applicable), and time.
  3. If the surgeon did it, check whether a different code type applies under the payer’s policy, such as moderate sedation codes. If not, write off the CO amount.
  4. Appeal only if the payer’s policy allows separate payment in this situation and it was misapplied.

How to prevent it

  • Separate rendering providers in charge entry for surgical and anesthesia services.
  • Know each payer’s rules on surgeon-administered blocks and sedation.
  • Review anesthesia claims for rendering NPI and modifiers before submission. The Claims Validator can flag mismatched rendering providers. See NCCI bundling denials for more on bundled services.

Specialty notes

Surgical specialties, pain management, and ambulatory surgery centers see this code most. Anesthesia groups may see it when their provider data is overwritten by the surgeon’s information in shared billing systems.

Remark codes that may appear with CO-194

  • N19 (Procedure code incidental to primary procedure.): The service is incidental to the primary procedure.
  • N203 (Missing/incomplete/invalid anesthesia time/units.): Anesthesia time or units are missing or invalid, sometimes seen when anesthesia billing data is incomplete.
  • CO-97 (The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.): Payment is included in the allowance for another service, the general bundling code.
  • CO-B20 (Procedure/service was partially or fully furnished by another provider.): The procedure or service was partially or fully furnished by another provider.
  • CO-170 (Payment is denied when performed/billed by this type of provider.): Payment denied for this type of provider.

CO-194 FAQ

Can a surgeon ever bill anesthesia separately?

Generally not under Medicare and many commercial payers. Local anesthesia and moderate sedation by the surgeon follow their own coding rules, and payers' policies differ, so check the specific payer.

What if a separate anesthesia provider did the anesthesia?

Then the claim may have the wrong rendering provider. Correct the rendering NPI in box 24J to the anesthesia provider and resubmit, with anesthesia modifiers and time.

Does CO-194 apply to moderate sedation?

It can, depending on how the payer classifies it. Moderate sedation has its own codes and rules that differ from anesthesia services by a separate anesthesia provider.

Can I bill the patient for anesthesia denied with CO-194?

No. Under the CO group code the provider absorbs the amount, since the payer considers the anesthesia part of the surgical payment.