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N439 Remark Code: Missing Anesthesia Physical Status

N439 means the anesthesia physical status report or indicator is missing. Anesthesia claims usually need a physical status modifier (P1 through P6) describing the patient's overall health, and the payer did not find one on the claim or supporting records.

Quick facts

Code
N439 (RARC N439)
Status
Active In use since July 1, 2008.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The anesthesia line cannot be processed without the physical status information. The provider corrects and resubmits; the patient is not billed.
Official description
Missing anesthesia physical status report/indicators.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N439 means

Anesthesia claims describe more than the procedure. They also capture how sick the patient was, using the physical status classification. That value is reported as a modifier from P1 to P6. N439 says the payer did not receive this physical status information at all, so it could not finish processing the anesthesia service.

N439 usually appears with CARC 16.

Common causes

  • Modifier left off the line. The anesthesia line carried a provider modifier (such as one showing personal performance or medical direction) but no P modifier.
  • Too many modifiers. The claim had more modifiers than the line could hold, and the P modifier was dropped by the billing system.
  • Not captured from the anesthesia record. The physical status was documented, but charge entry did not pull it.
  • Payer-specific report requirement. Some payers want the physical status on a separate report or attachment as well.

How to fix it

  1. Pull the anesthesia record and find the physical status the provider assigned in the pre-anesthesia evaluation.
  2. Add the P modifier to the anesthesia line in CMS-1500 box 24D, in the order the payer requires relative to other anesthesia modifiers.
  3. Check whether the payer needs anything else, such as a report or supporting documentation.
  4. Submit a corrected claim with resubmission code 7 in box 22 and the original claim number.

How to prevent it

Make physical status a required field in your anesthesia charge capture, so a claim cannot be created without it. Review modifier ordering rules for each major payer, since anesthesia lines often carry several modifiers.

Codes that may appear with N439

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim lacks information needed for adjudication; N439 identifies the physical status indicator.
  • CO-4 (The procedure code is inconsistent with the modifier used.): Can appear when the modifiers on the anesthesia line don't fit the code, including a missing physical status modifier.
  • N440 (Incomplete/invalid anesthesia physical status report/indicators.): The physical status information is present but incomplete or invalid.
  • N203 (Missing/incomplete/invalid anesthesia time/units.): Anesthesia time or units are missing, incomplete, or invalid.
  • N443 (Missing/incomplete/invalid total time or begin/end time.): The total time or begin and end time is missing, incomplete, or invalid.

N439 FAQ

What are the physical status modifiers?

P1 through P6 follow the American Society of Anesthesiologists physical status classification, from a normal healthy patient (P1) to a declared brain-dead patient whose organs are being removed for donation (P6).

Do all payers pay extra for higher physical status?

No. Some payers add base units for more severe physical status; others, including Medicare, do not pay extra. Many still require the modifier for reporting.

Who documents physical status?

The anesthesia provider assigns it during the pre-anesthesia evaluation, and it should appear in the anesthesia record.