CARC CO-45 Contractual Adjustment & Silent PPO Forensic Audit
Charge Exceeds Fee Schedule / Maximum Allowable Amount — How to stop silent PPO repricing networks, verify payer contractual rates, and eliminate unearned contractual write-offs.
Claim Adjustment Reason Code (CARC) CO-45 is the single largest line-item adjustment in medical billing. In theory, CO-45 represents the legitimate contractual discount between a provider billed charge and the insurer contracted allowable rate. However, unscrupulous commercial payers routinely exploit CO-45 by routing claims through "silent PPOs" (third-party repricing networks like MultiPlan, Zelis, or Viant) without proper authorization, or by paying below contracted fee schedule rates. In-house billers blindly write off these adjustments without auditing the underlying math. Our forensic audit verifies every CO-45 adjustment against your signed payer contracts.
Audit red flags
- Explanation of Benefits (EOB) references an unfamiliar repricing network (MultiPlan, Zelis, Data iSight) when the provider has no direct contract.
- Contracted commercial payer reimbursing less than the published baseline fee schedule rate attached to your provider agreement.
- Practice billing software automatically writing off all balances with Reason Code 45 without running contractual rate validation.
- Health plans applying multiple cascading fee schedule discounts to a single claim line.
Audit action plan
- 1. Payer Fee Schedule Contract Matrix Mapping — Digitize signed payer contracts and upload exact fee schedules into our auditing engine to verify each ERA 835 line payment.
- 2. Silent PPO Discount Invalidation Notices — Audit out-of-network claims for unauthorized rental network repricing and issue immediate demand letters rejecting illicit discounts under state contract law.
- 3. Automated Write-off Threshold Guardrails — Configure billing software to halt automated posting of CO-45 adjustments whenever the net paid amount falls below 105% of Medicare baseline.
Codes reviewed
- CARC CO-45 — Charge exceeds fee schedule / maximum allowable amount
- Silent PPO Repricing — Third-party repricing networks taking 20-40% haircuts
- RARC N522 — Duplicate or secondary discounting applied
- EHR Auto-Writeoff — Automated 835 zero-touch ERA balance reduction
Frequently asked questions
What is a Silent PPO and how does it affect CO-45 adjustments?
A silent PPO occurs when an insurance company accesses a discounted fee schedule through a secondary network without provider knowledge or consent, applying a deep CO-45 contractual write-off even though the provider never agreed to treat that specific plan as in-network.
Can a practice challenge a CO-45 contractual write-off?
Yes. If the health plan paid less than the contracted fee schedule rate, or if an unauthorized repricing entity discounted an out-of-network claim, the adjustment can be challenged and recovered through formal contractual underpayment appeals.