Medical billing denial codes tell you why a payer did not pay a claim. Each code points to a specific problem, like missing data or a service that needs prior approval. When you learn to read these medical billing denial codes, you can fix claims faster and stop the same denials from coming back.
What Are Medical Billing Denial Codes?
When a payer processes a claim, it sends back a Claim Adjustment Reason Code, or CARC. This short code explains the action the payer took. “CO” means the provider is responsible, while “PR” means the patient owes the balance. Once you know the code, you know your next step.
The Most Common Medical Billing Denial Codes
A few codes cause most of the denials US practices see. Here are the ones to know:
- CO-16 – Missing information. The claim lacks data the payer needs. Fix it, then resubmit.
- CO-18 – Duplicate claim. The same claim was sent twice. Check the status before resending.
- CO-22 – Coordination of benefits. Another payer should be billed first.
- CO-29 – Timely filing. The claim arrived after the filing deadline.
- CO-45 – Charge exceeds fee schedule. Your charge is above the allowed amount; this is a contract adjustment.
- CO-50 – Not medically necessary. The payer wants documentation that supports the service.
- CO-97 – Bundled service. Payment is already included in another service that was paid.
- CO-197 – Authorization missing. The service needed prior authorization that was not on file.
- PR-1, PR-2, PR-3 – Patient responsibility. Deductible, coinsurance, or copay the patient must pay.
How to Prevent Medical Billing Denial Codes
Most denials are preventable. These habits stop the common medical billing denial codes before they happen:
- Check eligibility and benefits before every visit.
- Confirm prior authorization for services that need it.
- Scrub claims for errors before you submit them.
- Track filing deadlines for each payer.
- Document medical necessity clearly in the chart.
- Review denial trends each month and fix the root cause.
How to Read a Denial in Three Steps
Every denial follows the same basic pattern. Once you learn to read it, you can act fast. Use these three steps:
- Find the code. Look for the CARC code on the remittance advice.
- Sort the responsibility. “CO” means you handle it; “PR” means it goes to the patient.
- Take the right action. Fix and resubmit, send a corrected claim, appeal, or bill the patient.
The faster you read and route each denial, the more you recover. Claims that sit untouched are the ones that age out and turn into write-offs. It also pays to group denials by reason each month. If one code keeps appearing, the problem is in your process, not the payer. Fixing that single step can remove dozens of future denials at once.
A small set of codes drives most denials, so you do not need to memorize the whole list. Focus on the handful above, build a simple fix for each, and you will clear most rejections quickly. Over time, your clean-claim rate rises and your team spends far less time on rework.
Key Takeaways
- Denial codes (CARC) explain why a payer did not pay a claim.
- A few codes cause most denials, like CO-16, CO-197, and CO-50.
- Prevention beats rework: verify, authorize, scrub, and document.
Frequently Asked Questions
Quick answers to the questions US practices ask most about claim denials.
What are medical billing denial codes?
They are Claim Adjustment Reason Codes (CARC) that a payer sends back to explain why a claim was adjusted or denied. Each code points to a specific issue, such as missing information or a missing authorization.
What is the difference between CO and PR denial codes?
“CO” stands for contractual obligation, meaning the provider is responsible for the adjustment. “PR” stands for patient responsibility, meaning the balance goes to the patient, such as a deductible or copay.
What is the most common denial code?
CO-16, which flags missing or incomplete information, is among the most frequent. Other common ones include CO-197 for a missing authorization and CO-50 for a medical necessity issue.
What does denial code CO-197 mean?
CO-197 means the service required prior authorization that was not obtained or not on file. To fix it, get the authorization if possible and appeal, or request a retro authorization from the payer.
How do I fix a denied claim?
First read the CARC code to find the reason. Then correct the issue, whether it is missing data, an authorization, or a coding error. Finally, resubmit a corrected claim or file an appeal before the payer’s deadline.
How can I prevent claim denials?
Verify eligibility before visits, confirm prior authorizations, scrub claims for errors, document medical necessity, and track filing deadlines. Reviewing denial trends each month helps you fix the root cause.
Squadyen Health works denials fast and tracks the root causes so they do not return. Want fewer denials and faster payments? Book a free denial review.