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N858 Remark Code: State OON Emergency Care Law Applied

N858 is an alert that state regulations under an Out of Network Medical Emergency Care Act were applied when processing the claim. It also tells you the payment amount can be disputed using the state's documented appeal, grievance, or arbitration process.

Quick facts

Code
N858 (RARC N858)
Status
Active In use since November 1, 2021.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • PR (Patient Responsibility): Patient cost sharing was limited under the state law's protections.
  • CO (Contractual Obligation): Amounts adjusted under the state law aren't billable to the patient.
Official description
Alert: State regulations relating to an Out of Network Medical Emergency Care Act were applied to the processing of this claim. Payment amounts are eligible for dispute following the state's documented appeal/ grievance/ arbitration process.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N858 means

Many states have laws protecting patients from surprise bills after out-of-network emergency care, and some also set how out-of-network providers are paid and how they can dispute payment. N858 is a general alert that one of these state laws governed the claim. Unlike N844, it doesn’t name the state.

The alert adds a practical point: if you disagree with the payment, the state’s own process, whether an appeal, grievance, or arbitration, is the route.

What to do

  1. Bill the patient only the PR amount reported.
  2. Identify the applicable state law and its dispute procedure and deadlines.
  3. Compare the payment with what the law provides, and gather supporting data if you plan to dispute.
  4. File the dispute through the state process within its timeframe if the payment seems too low.

Codes that may appear with N858

  • CO-45 (Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement.): The charge was reduced to the amount allowed under state law.
  • PR-2 (Coinsurance Amount): Coinsurance calculated under the state law.
  • N844 (This claim, or a portion of this claim, was processed in accordance with the Nebraska Legislative LB997 July 24, 2020 - Out of Network Emergency…): The claim was processed under Nebraska's specific out-of-network emergency care act.
  • N859 (Alert: The Federal No Surprise Billing Act was applied to the processing of this claim.): The federal No Surprises Act was applied instead of a state law.
  • N830 (Alert: The charge[s] for this service was processed in accordance with Federal/ State, Balance Billing/ No Surprise Billing regulations.): A broader balance billing alert describing what can't be collected.

N858 FAQ

Which state law applies?

The remark doesn't name the state. It's generally the state regulating the patient's plan. Ask the payer if it isn't clear.

How do I dispute the payment?

Use the state's documented process named in the alert, which may be an appeal, grievance, or arbitration. Deadlines apply.

Can I bill the patient more?

Generally not beyond the PR amount the payer reported.