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CO-P23 Denial Code: PIP or MPC Fee Schedule Adjustment

CO-P23 means an auto insurer reduced the billed charge to the amount allowed under the jurisdiction's Medical Payments Coverage (MPC) or Personal Injury Protection (PIP) fee schedule. It's the auto no-fault version of a fee schedule reduction.

Quick facts

Code
CO-P23 (CARC P23)
Status
Active In use since November 1, 2013; last modified July 1, 2017.
Code set
Claim Adjustment Reason Codes (CARC)
Group codes
  • CO (Contractual Obligation): The usual group. The reduction is required by the state fee schedule; many no-fault states bar billing the claimant for the difference.
Official description
Medical Payments Coverage (MPC) or Personal Injury Protection (PIP) Benefits jurisdictional fee schedule adjustment. Usage: If adjustment is at the Claim Level, the payer must send and the provider should refer to the 835 Class of Contract Code Identification Segment (Loop 2100 Other Claim Related Information REF). If adjustment is at the Line Level, the payer must send and the provider should refer to the 835 Healthcare Policy Identification Segment (loop 2110 Service Payment information REF) if the regulations apply. To be used for Property and Casualty Auto only.
X12 Claim Adjustment Reason Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What CO-P23 means

CARC P23 is a Medical Payments Coverage (MPC) or Personal Injury Protection (PIP) benefits jurisdictional fee schedule adjustment. X12 limits it to property and casualty auto claims. It replaced deactivated CARC Y3.

In states that regulate auto medical fees, the carrier pays the lower of your charge or the state’s no-fault fee schedule amount. The difference is reported as CO-P23. Some states base the schedule on their workers’ comp fee schedule; others set it as a percentage of the Medicare fee schedule or use a separate schedule.

It’s the auto counterpart to CO-P12 for workers’ comp and CO-P29 for liability coverage, and the P&C cousin of CO-45 in group health.

Example: you bill $180 for a service. The state’s PIP schedule allows $96 in your region. The auto carrier pays $96 and reports CO-P23 for $84. Under many no-fault laws, the claimant owes nothing more.

Common causes

  • Charges above the no-fault fee schedule, which is normal.
  • Wrong schedule version applied for the date of service.
  • Wrong region or locality factor.
  • Modifiers ignored, changing the priced service.
  • Facility and professional schedules confused.

How to check it

  1. Find the state’s no-fault fee schedule for the date of service.
  2. Calculate the expected allowance including region and modifier rules.
  3. Compare to the payment.
  4. Post matching reductions as adjustments; don’t bill the claimant where state law prohibits it.
  5. Dispute errors through reconsideration and the state’s no-fault dispute process.

How to prevent problems

  • Load no-fault fee schedules for each state you serve.
  • Update them when states publish revisions.
  • Monitor auto payments. An ERA Analyzer can compare CO-P23 allowances to expected amounts.

Specialty notes

Chiropractic, PT, and imaging providers in no-fault states rely heavily on PIP payments, so small fee schedule errors across many visits can add up.

Remark codes that may appear with CO-P23

  • N603 (This fee is calculated according to the New Jersey medical fee schedules for Automobile Personal Injury Protection and Motor Bus Medical Expense…): An example: fees calculated under New Jersey's auto PIP fee schedules.
  • N604 (In accordance with New York No-Fault Law, Regulation 68, this base fee was calculated according to the New York Workers' Compensation Board Schedule…): An example: New York no-fault fees based on the state's workers' comp schedule.
  • N608 (The fee schedule amount allowed is calculated at 110% of the Medicare Fee Schedule for this region, specialty and type of service.): An example of a schedule set as a percentage of the Medicare fee schedule.
  • CO-Y3Deactivated (Medical Payments Coverage (MPC) or Personal Injury Protection (PIP)): The deactivated code that CARC P23 replaced.
  • CO-P12 (Workers' compensation jurisdictional fee schedule adjustment.): The workers' comp fee schedule adjustment.
  • CO-P29 (Liability Benefits jurisdictional fee schedule adjustment.): The liability coverage fee schedule adjustment.
  • CO-P5 (Based on payer reasonable and customary fees.): Reasonable and customary pricing when no legislated schedule applies.

CO-P23 FAQ

Which states have auto no-fault fee schedules?

Several no-fault states set medical fee schedules for PIP claims, some based on their workers' comp schedules and others on a percentage of Medicare. Rules differ by state, so check the one that governs the claim.

Can I bill the injured person the difference?

In many no-fault states, no. Providers accepting PIP payment are generally limited to the fee schedule amount. Check state law.

How do I verify a CO-P23 amount?

Look up the state's no-fault fee schedule for the date of service, calculate the allowance for your code and region, and compare it to the payment.

Is CO-P23 used for health plan claims?

No. It's limited to property and casualty auto claims.

Is CO-P23 a denial?

No. The line was paid at the fee schedule amount. It becomes a problem only if the allowance is lower than the schedule actually permits.