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N504 Remark Code: Work Status Report Incomplete

N504 means the carrier received a work status report but found it incomplete or invalid. It may not state a clear work status, may lack specific restrictions or effective dates, may be unsigned, or may conflict with the visit documentation.

Quick facts

Code
N504 (RARC N504)
Status
Active In use since July 1, 2008.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The treating provider must correct the report. The injured worker is not billed for the adjustment.
Official description
Incomplete/invalid Work Status Report.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N504 means

The carrier received the work status report for the visit but could not rely on it. Since employers and adjusters act on these reports, deciding whether to pay wage benefits or offer modified duty, a report that leaves questions open is treated as incomplete. N504 is the incomplete-or-invalid companion to N503.

Typical gaps

  • No clear status. The report does not say whether the worker is off work, on modified duty, or at full duty.
  • Vague restrictions. Phrases like limited activity with no measurable limits.
  • Missing dates. No effective date, end date, or next reassessment date.
  • Authentication. Unsigned, or signed by someone other than the treating provider when the state requires the treating physician.
  • Conflicts. The report and the visit note describe different restrictions.

How to fix it

  1. Identify the specific deficiency from the carrier’s notice or a call to the adjuster.
  2. Have the treating provider complete or clarify the status, restrictions, and dates.
  3. Label the revised report as corrected and send it with the claim number and date of service.
  4. Ask the carrier to reprocess the bill, or rebill according to state rules.
  5. Share the corrected report with the employer if required.

How to prevent it

Use a structured work status form with required fields for status, specific restrictions, effective dates, and the next visit. Structured fields prevent the vague free-text entries that most often lead to N504.

Codes that may appear with N504

  • CO-251 (The attachment/other documentation that was received was incomplete or deficient.): The report was received but was deficient.
  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Missing or invalid information prevented adjudication.
  • CO-P1 (State-mandated Requirement for Property and Casualty, see Claim Payment Remarks Code for specific explanation.): A state-mandated property and casualty reporting requirement was not satisfied.
  • N503 (Missing Work Status Report.): No work status report was received.
  • N496 (Incomplete/invalid Supplemental Medical Report.): A supplemental medical report, which may include work status, is incomplete or invalid.
  • N502 (Incomplete/invalid Vocational Report.): A vocational report is incomplete or invalid instead.

N504 FAQ

What makes a work status report unusable?

Vague statements like light duty with no specific limits, missing start or end dates, no next visit date, no provider signature, or restrictions that contradict the visit note.

Do restrictions need to be specific?

Carriers and employers generally need concrete limits, for example weight limits, hours, or activities to avoid, to decide whether modified work is available. Vague wording often triggers N504.

Should I correct the report or the note?

Correct whichever is wrong, but only with the treating provider's input. If the report and note conflict, the provider should clarify which reflects the actual assessment.