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N598 Remark Code: Health Insurance Is Primary

N598 means the payer determined that the patient's health care policy is primary for these services. Bill the health insurer first, then send any remaining balance, with its remittance, to this payer if it provides secondary coverage.

Quick facts

Code
N598 (RARC N598)
Status
Active In use since July 15, 2013.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • OA (Other Adjustment): The amount is not denied outright; it belongs with the primary health plan first.
  • CO (Contractual Obligation): Some carriers report the misdirected primary billing under CO. It is still a coordination issue, not a final denial.
Official description
Health care policy coverage is primary.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N598 means

After an accident, it’s common to bill the auto insurer first. But depending on state law and the policy’s terms, the auto carrier may be secondary to the patient’s health insurance. N598 is the auto or injury carrier telling you that, for this patient, the health care policy should pay first.

It typically comes with CARC 22 (another payer may be responsible under coordination of benefits) or P21.

Common causes

  • The policyholder chose coordinated or secondary auto medical coverage.
  • State rules make health insurance primary for certain injured people.
  • The patient’s health coverage was not collected at intake, so the claim went to the auto carrier by default.

How to fix it

  1. Get the patient’s health insurance details and verify eligibility for the date of service.
  2. Bill the health plan as primary, noting that the services are accident-related. The health plan may ask for accident details (CMS-1500 box 10b) and the auto claim information.
  3. Send the balance to the auto carrier after the health plan pays, with the health plan’s EOB.
  4. Watch filing limits at the health plan, which may be close if time has passed. See timely filing denials.

How to prevent it

For accident visits, collect health insurance and auto claim information at the same time, and ask the auto adjuster at the start whether its medical coverage is primary or secondary. See eligibility and COB denials.

Codes that may appear with N598

  • OA-22 (This care may be covered by another payer per coordination of benefits.): The care may be covered by another payer per coordination of benefits.
  • CO-P21 (Payment denied based on the Medical Payments Coverage (MPC) and/or Personal Injury Protection (PIP)): Denied under PIP or medical payments jurisdictional rules, such as a coordination provision.
  • N577 (Personal Injury Protection (PIP)): Identifies Personal Injury Protection coverage.
  • N579 (Medical Payments Coverage (MPC).): Identifies Medical Payments Coverage.
  • N4 (Missing/Incomplete/Invalid prior Insurance Carrier(s)): The prior payer's EOB is missing, which you may see when billing secondary.

N598 FAQ

Isn't auto insurance always primary for accidents?

No. Depending on the state and the policy, auto medical benefits can be secondary to health insurance, or the policyholder may have chosen coordinated coverage.

What do I send to the auto carrier after the health plan pays?

A claim for the remaining balance with the health plan's EOB or remittance showing what it paid and what the patient owes.

What if the patient has no health insurance?

Tell the auto carrier and provide proof if requested. The carrier may then process the claim as primary.