CommonContractual Obligation (CO)Duplicate Claim

CO-97: Payment adjusted because already paid for this procedure/service

This procedure or service has already been paid. The payer records show a prior claim for the same procedure, same patient, same date of service has already been adjudicated and paid. This is similar to CO-18 (duplicate) but specifically indicates payment was already issued.

Common Causes

  • Duplicate claim submission
  • Corrected claim submitted without void/replace frequency code
  • Same procedure billed by multiple providers for the same encounter
  • Crossover claim already processed by secondary payer

How to Resolve CO-97

  1. 1Check your payment records to confirm the original claim was indeed paid
  2. 2If this is a corrected claim, resubmit with frequency code 7 and original ICN/DCN
  3. 3If the procedures are distinct services, add modifiers to distinguish them and appeal
  4. 4If already paid, no action needed -- write off the duplicate

How to Prevent CO-97 Denials

  • Track all claim submissions and payments to prevent resubmission of paid claims
  • Use proper frequency codes when correcting or replacing claims
  • Implement duplicate claim detection in your billing workflow

Related Denial Codes

CO-18Common

Duplicate claim/service

CO-4Very Common

Procedure code inconsistent with modifier or not valid for date of service

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