CO 24 Denial Code - A Complete Guide to Causes, Fixes & Prevention

What is a CO 24 Denial Code?

The CO 24 denial code signifies “Charges exceed your contracted/legislated fee arrangement.” It occurs when a provider bills an amount higher than the payer’s allowable rate, commonly affecting Medicaid, Medicare, and commercial insurers.

Top 10 Reasons for CO 24 Denials

Incorrect Fee Schedule: Billing rates not updated to match payer contracts.
State-Specific Medicaid Caps: Charging above Medicaid’s legislated rates.
Modifier Misuse: Missing modifiers like -GY (non-covered service) or -GA (waiver of liability).
Duplicate Claims: Overlapping charges for the same service.
Timely Filing Issues: Late resubmission of adjusted claims.
Contractual Obligations: Ignoring payer-specific rate agreements.
CPT/HCPCS Mismatch: Services billed under incorrect codes.
Fee-for-Service Limits: Exceeding annual visit caps (e.g., Medicaid therapy limits).
Third-Party Liability: Patient has alternate coverage (e.g., auto insurance).
Credentialing Errors: Provider not in-network under current contract.

How to Fix CO 24 Denials: Step-by-Step

Audit the Claim: Compare billed amount to payer’s fee schedule.
Verify Contracts: Ensure rates align with Medicaid/insurer agreements.
- Example: Medicaid may cap 99213 visits at 75, butyoubilled75, butyoubilled90.
Apply Modifiers: Use -GY if the service isn’t covered but the patient was informed.
Adjust & Resubmit: Reduce charges to the allowable rate and append modifier -CO (contractual obligation).
Prevent Recurrence: Update billing software with latest payer rates.

Pro Tip: Use ERA (Electronic Remittance Advice) data to pinpoint CO 24 triggers.

CO 24 in Medicaid - State-Specific Fixes

Florida Medicaid: Check rates via FL Medicaid Fee Schedule.
Texas Medicaid: Verify EPSDT (Child Health) service limits.
California Medi-Cal: Use TARs (Treatment Authorization Requests) for overrides.

Related Denial Codes

Code	Description	vs. CO 24
CO 18	Duplicate claim	CO 24 = Overcharge; CO 18 = Repeat claim
CO 20	Missing/invalid patient ID	Fixes require ID verification.
CO 247	Non-covered service (payer-specific)	Unlike CO 24, this denies coverage, not rates.

Final Thoughts

By understanding the causes, consequences, and potential solutions associated with CO 24, healthcare providers and billing professionals can navigate the complexities of the reimbursement process more efficiently.

Automate Fee Schedules: Tools like Way star or Change Healthcare update rates in real-time.
Staff Training: Conduct quarterly sessions on payer contracts.
Pre-Bill Audits: Flag potential overcharges before claims are sent.