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N743 Remark Code: May Be a Work-Related Injury

N743 means the payer adjusted this claim because the services may be related to an employment accident. The payer suspects workers' compensation should pay and wants that confirmed or ruled out before it pays as the health plan.

Code: N743 (RARC N743)
Status: Active In use since March 1, 2015.
Code set: Remittance Advice Remark Codes (RARC)
Group codes: CO (Contractual Obligation): The payer holds back payment as the provider's issue until the work-related question is resolved.
OA (Other Adjustment): Some payers use OA to show another payer may be responsible. It is not patient balance.
Official description: Adjusted because the services may be related to an employment accident.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What N743 means

Health plans generally do not pay for care that workers’ compensation should cover. N743 is used when the payer suspects, but has not confirmed, that the treatment stems from an employment accident. It adjusts the claim and waits for clarification.

The wording “may be related” is important. Unlike N728, where a comp carrier has reported responsibility, N743 is a question the payer wants answered. It commonly accompanies CARC 19, CARC 22, or CARC 227.

Common causes

The claim’s employment-related indicator (box 10a on the CMS-1500) was marked yes.
The diagnosis codes include external cause or injury codes suggesting a workplace event.
The patient did not return the payer’s accident questionnaire.
A previous claim for the same injury was billed to a workers’ compensation carrier.

How to fix it

Ask the patient where and how the injury happened.
If it was not work related, check box 10a and the injury coding on the claim. Send a corrected claim with resubmission code 7 if they were wrong, and have the patient complete any payer questionnaire.
If it was work related, bill the workers’ compensation carrier with the employer and claim details.
If the carrier denies liability, forward its written decision to the health plan and request reprocessing.

How to prevent it

Ask about work injuries at registration for any injury visit, and make sure box 10a reflects the answer. Front-end claim checks can flag injury diagnoses that lack accident information before submission.

Codes that may appear with N743

OA-19 (This is a work-related injury/illness and thus the liability of the Worker's Compensation Carrier.): The injury or illness is work related and the workers' compensation carrier's liability.
OA-22 (This care may be covered by another payer per coordination of benefits.): Another payer may be responsible under coordination of benefits.
CO-227 (Information requested from the patient/insured/responsible party was not provided or was insufficient/incomplete.): Information requested from the patient, such as an accident questionnaire, was not provided.

N744 (Adjusted because the services may be related to an auto/other accident.): The same kind of adjustment for a possible auto or other accident.
N728 (A workers' compensation insurer has reported having ongoing responsibility for medical services (ORM) for this diagnosis.): A workers' compensation carrier has confirmed ongoing responsibility, not just a suspicion.
N305 (Missing/incomplete/invalid injury/accident date.): The injury or accident date is missing or invalid.
CO-P2 (Not a work related injury/illness and thus not the liability of the workers' compensation carrier): A workers' compensation carrier's finding that the injury is not work related.

N743 FAQ

Why does the payer think this is work related?

Often because of the diagnosis codes, an accident indicator on the claim, or information from the patient. The payer is asking you to confirm before it pays.

What if the injury did not happen at work?

Have the patient answer the payer's accident questionnaire or contact the payer, and make sure the claim does not mark the condition as employment related. Then ask for reprocessing.

What if it really was a work injury?

Bill the employer's workers' compensation carrier. If the carrier denies the claim, send its denial to the health plan.

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