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N643 Remark Code: Listed as Non-Covered in State Schedule

N643 means the service is marked Not Covered (NC) in the state fee schedule that governs the claim, so the carrier did not pay it. It is used mostly on workers' compensation and auto injury bills priced under a state-mandated schedule.

Quick facts

Code
N643 (RARC N643)
Status
Active In use since July 15, 2013.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The charge is not payable under the state schedule and is typically the provider's write-off. Whether the injured person can be billed is controlled by state law and is often prohibited.
  • PR (Patient Responsibility): Occasionally used when the carrier indicates the patient may be responsible. Confirm the jurisdiction allows it before sending a bill.
Official description
The services billed are considered Not Covered or Non-Covered (NC) in the applicable state fee schedule.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N643 means

Workers’ compensation and some auto no-fault systems pay under a state-adopted fee schedule. Besides listing allowed amounts, these schedules assign statuses to codes. One common status is NC, for “not covered” or “non-covered”: the jurisdiction has decided the code is not separately payable under that system.

N643 says the carrier looked up your service in the applicable state schedule, found it marked NC, and adjusted it to zero. The accompanying CARC is often 96 or 162.

Why a service may be NC

  • The state bundles it into another service, so paying it separately would double-pay.
  • The state requires a different code for that type of work, often a state-specific code.
  • The service falls outside the scope of what the system pays for, such as certain administrative or convenience items.
  • The wrong schedule was used. If your claim was priced under a state or schedule year that does not apply, the NC status may be wrong.

What to do

  1. Confirm the jurisdiction and date of service, and make sure the carrier used that state’s schedule for that period.
  2. Read the ground rules for the code in the schedule. They often explain the NC status and name any alternative code.
  3. Correct and resubmit if a different code properly describes the service you documented.
  4. Seek pre-approval or dispute where the state allows payment of NC services by agreement or on review; the process varies by state.
  5. Do not bill the patient unless state law clearly permits it.

How to prevent it

When treating injured workers or auto claimants, check each planned service against the relevant state’s schedule before billing. Keep the current version of each schedule you bill under, since statuses can change when a state updates its schedule.

Codes that may appear with N643

  • CO-96 (Non-covered charge(s).): Non-covered charge, with N643 identifying the state schedule as the reason.
  • CO-162Deactivated (State-mandated Requirement for Property and Casualty, see Claim Payment Remarks Code for specific explanation.): State-mandated requirement for property and casualty claims.
  • CO-220Deactivated (The applicable fee schedule/fee database does not contain the billed code.): The code is missing from the fee schedule entirely, rather than listed as not covered.
  • N632Deactivated (According to the Official Medical Fee Schedule this service has a relative value of zero and therefore no payment is due.): The service is listed but has a relative value of zero, so no payment is due.
  • N631 (Medical Fee Schedule does not list this code.): The code is not in the schedule, but the payer allowed a comparable service.
  • N448 (This drug/service/supply is not included in the fee schedule or contracted/legislated fee arrangement.): The item is not in the fee schedule or contracted arrangement.

N643 FAQ

Is there another code I can bill instead?

Sometimes. Some state schedules mark a code NC because a different code or a bundled service is meant to be used. Check the ground rules of the schedule before choosing another code, and only bill what the documentation supports.

Can I bill the injured worker for an NC service?

Many states restrict or prohibit billing injured workers for services related to a compensable injury. Check the specific state's rules.

Does N643 mean the treatment was not medically necessary?

No. It is a fee schedule status, not a clinical judgment. The service may be appropriate care that the state schedule simply does not pay for.