What is the CO 23 Denial Code?


This denial is triggered when the amount paid by primary insurance is less than the secondary insurance's allowable amount, but the primary's allowed amount is still higher than the secondary's. In essence, CO 23 throws a spotlight on the prior payer's decisions, encompassing their payments and adjustments.  

Illustrating Denial CO 23 with an Example: 

Let's say a patient is insured by Aetna (Primary) and Cigna (Secondary). Here's a hypothetical billing scenario: 

Primary Aetna's adjudication: 

  • Total Billed: $250.00 
  • Contractual Adjustment: $50.00
  • Allowed: $200.00
  • Paid: $170.00
  • Coinsurance: $30.00 

Secondary Cigna's adjudication: 

  • Allowable: $190.00
  • Paid by Aetna: $170.00
  • Net Allowed by Cigna: $20.00
  • Balance denied with CO 23: $10.00 

In this illustration, Cigna's allowable stands at $190. But Aetna has already covered $170. This creates a net allowable of $20 from Cigna's end. The outstanding $10 is thus tagged with the CO 23 Denial Code. 

Navigating CO 23 Denials: 

  • Audit the Insurance Details: Confirm balances are accurately pending with the secondary insurer. 
  • Touch Base with Primary Insurer: If the primary insurer has the CO 23 flag, contact them for a claim reevaluation. 
  • Examine the Secondary's Fee Schedule: Delving into the secondary insurer’s fee schedule can provide clarity on allowable amounts. 
  • Assess Net Allowables: Determine the secondary insurer's net allowable and see how they reached that conclusion, ensuring proper application to patient responsibilities. 

By embracing a thorough approach and integrating with an efficient Revenue Cycle Management (RCM) system, such discrepancies can be minimized, paving the way for more streamlined claim processes. 

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