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N311 Remark Code: Return to Work Date Invalid

N311 means the date the patient was authorized to return to work was missing, incomplete, or invalid. It typically comes from workers' compensation or disability-related payers that track when a clinician released the patient to work.

Quick facts

Code
N311 (RARC N311)
Status
Active In use since December 2, 2004.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The provider must supply or correct the date; the adjustment is not billed to the patient.
Official description
Missing/incomplete/invalid authorized to return to work date.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N311 means

In workers’ compensation and disability programs, the date a treating clinician authorizes the patient to go back to work is a key data point. It affects wage-replacement benefits and helps the carrier judge whether ongoing treatment is consistent with the patient’s status. N311 says the carrier needed that date on the claim and didn’t get a valid one.

It is usually paired with CARC 16. The service isn’t being denied on its merits; the carrier is asking for work-status information.

Common causes

  • The clinician documented a work release, but the date never made it to the claim.
  • The date entered is earlier than the date the patient stopped working, or earlier than the injury date.
  • Box 16 has only a ‘from’ date, with no ‘to’ date, and the carrier’s rules require both.
  • A later work-status update changed the return date, and the claim still shows the old one.
  • The carrier requires the date on its own form or attachment, and it was sent only on the claim, or not at all.

What to do

  1. Find the most recent work-status note or release form signed by the treating clinician.
  2. Confirm the authorized return-to-work date, including any restrictions noted.
  3. Report it where the carrier specifies, whether box 16, an electronic date field, or a state work-status form.
  4. Check it’s consistent with the injury date and the last worked date.
  5. Resubmit according to the carrier’s correction process.

How to prevent it

Workers’ compensation claims need more data than typical health claims. Keep a checklist for each state and carrier, and make work-status updates a structured part of every visit note for these patients. When a clinician changes the release date, update billing at the same time. For more on data-driven denials, see our CARC 16 guide.

Codes that may appear with N311

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Missing or invalid information; N311 names the return-to-work date.
  • N316 (Missing/incomplete/invalid disability to date.): The disability 'to' date is missing or invalid.
  • N325 (Missing/incomplete/invalid last worked date.): The last worked date is missing or invalid.
  • N315 (Missing/incomplete/invalid disability from date.): The disability 'from' date is missing or invalid.

N311 FAQ

Which payers ask for a return-to-work date?

Mainly workers' compensation carriers and payers administering disability-related benefits. Most group health plans do not require it.

Where does it go on a CMS-1500?

Box 16 records the dates the patient was unable to work in their current occupation; the 'to' date often reflects when the patient can return. Some carriers have their own forms or fields, so follow their instructions.

What if the patient hasn't been released yet?

Report what the carrier asks for in that situation. Don't enter an estimated date as though it were an authorized release.