CO 97 Denial Code Explained – What It Means and How to Correct It

March 19, 2026 Share on

In medical billing, denial codes are indicators from insurance companies that explain why a claim or service was not paid. These codes help healthcare providers understand what went wrong and how to fix it. Learning about denial codes is important because it helps reduce claim rejections, avoid loss of revenue, and improve overall billing accuracy.

One common denial is the CO 97 Denial Code. This usually happens when services are billed separately even though they should be grouped together (bundled), or when the same service is billed more than once. If not handled correctly, it can lead to repeated denials and payment delays. 

By understanding why CO 97 description and how denials occur and correcting them properly, providers can increase their chances of getting claims approved and keep their billing process running smoothly.

CO-97 Denial Code Definition

The CO-97 denial code and action happens when an insurance company won’t pay separately for a service because it’s already included in another service. Basically, the denied service is considered part of a bigger procedure that’s already covered.

This doesn’t always mean a mistake was made. It usually reflects the way the insurance groups certain services together. For example, minor procedures, supplies, or tests may be included in the payment for a major procedure.

CO 97 Denial Code in Medical Billing

The CO 97 denial code is a common claim rejection in medical billing. It occurs when a payer determines that a billed service is already included in another procedure and cannot be reimbursed separately. Essentially, the service is considered “bundled” with another service.

Common Reasons for CO 97 Denial Code

A CO-97 denial happens when Medicare or another insurance payer decides not to pay for a service. Knowing why this happens can help prevent future problems. 

Some of the most common reasons include:

Service Already Included in Another Procedure

Sometimes, a service is considered part of a bigger procedure and cannot be billed separately.

Duplicate Billing

This happens when the same service is accidentally submitted more than once.

Incorrect Coding or Unbundling

Some services should be billed together, but if they are billed separately, the claim may be denied.

Payer-Specific Bundling Rules

Insurance companies may have rules that group certain procedures into a single payment.

Misunderstanding Coding Guidelines

Errors in reading or applying coding rules can cause claims to be submitted incorrectly.

CO 97 Denial Code Action and Medicare Guidelines

The CO 97 denial code (Medicare) usually happens because of bundling rules. In simple terms, this means Medicare sees one service as already included in another service, so it will not pay for both separately.

Medicare Guidelines

Medicare guidelines provide a framework to ensure accurate billing and proper reimbursement for healthcare services. These rules help prevent errors, fraud, and improper payments while promoting compliance with federal standards.

Key points include:

Bundling Rules: Certain services are considered part of a larger procedure and are not reimbursed separately.

National Correct Coding Initiative (NCCI): Ensures that services that are usually performed together are billed correctly.

Documentation Requirements: Claims must be supported with clear and complete medical records.

Eligibility & Coverage: Only services that meet Medicare’s criteria for medical necessity are reimbursable.

Denial Prevention: Understanding and following these guidelines reduces common denials such as CO-97.

Common Reasons for CO 97 Denials

Here are some simple reasons why Medicare may apply this denial:

• Service Already Included

A procedure is part of a bigger service, so it cannot be billed separately.

• Unbundling Services

Services that should be billed together are submitted as separate charges.

• Services That Don’t Go Together

Two procedures are billed together when they shouldn’t be.

• Missing or Incorrect Modifiers

Modifiers (special codes that explain services) are not added or used incorrectly.

Why This Matters

Understanding CO 97 is important because it helps providers:

• Avoid repeated claim denials
• Get paid faster
• Reduce billing errors
• Protect their revenue

By following Medicare’s coding rules and using correct documentation, healthcare providers can prevent these denials and improve their billing process.

Struggling with repeated CO 97 denials or unsure how to fix them?

Our medical billing experts can help you identify the root cause, correct claims, and reduce future denials.

Contact HMS Group Inc. today to smooth your billing process and improve reimbursements.

How to Fix CO 97 Denial Code (Solutions)

CO-97 denials happen when an insurance payer says a service you billed is already included in another service. Handling these denials correctly can help you get paid properly and prevent the same issue from happening again.

Check the Claim Carefully

Look at the claim that was denied. Identify which service was rejected and why. Compare the codes you billed with the documentation in the patient’s record.

Understand Bundling Rules

Some services are “bundled,” meaning they are considered part of another procedure. Check if the denied service falls under bundling rules, like those from the NCCI. Make sure you’re using updated coding guides.

Use Modifiers Correctly

If the service is separate and should be billed on its own, make sure you use the right modifiers (like modifier 59). Modifiers tell the payer that a service is distinct from other procedures.

Fix Mistakes and Resubmit

Once you find the problem, correct the codes or documentation and resubmit the claim. Include all supporting details to help it get approved.

Common Mistakes to Avoid

• Don’t bill bundled services separately – If a service is already included in another procedure, billing it alone can lead to a CO 97 denial.

• Use the right modifiers – Modifiers tell the payer if a service is separate or part of another. Missing or wrong modifiers can cause the claim to be rejected.

• Follow each payer’s rules – Medicare and other insurers have different rules about bundled services. Ignoring these rules increases the chance of denial.

• Provide clear documentation – Claims need clear explanations showing why a service should be billed separately. Incomplete or confusing documentation can lead to CO 97 denials.

How to Prevent CO 97 Denials

CO 97 denials happen when a service is considered part of another procedure and is not paid separately. 

You can reduce these denials by following a few key practices:

• Review your coding often to catch mistakes, follow the right standards, and fix errors before sending claims. This helps prevent denials.

• Make sure coders and billing staff know the latest rules about bundled services, modifiers, and payer requirements. Ongoing training keeps everyone accurate.

• Every insurance payer may have different rules about what can be billed separately. Check their policies before submitting claims.

• Detailed clinical notes explaining why each service was necessary to help support your billing. Clear records reduce mistakes and make appeals easier if needed.

Final Words

Understanding and managing CO 97 denials is very important for keeping your medical billing process smooth and accurate. These denials usually happen because of bundled services, wrong use of modifiers, or missing documentation.

By learning common mistakes and following best practices like doing regular audits, training your staff, following payer rules, and keeping good documentation you can reduce denials and get paid faster.

Accurate billing helps your practice stay financially healthy and avoids delays in payments. 

Take action now: review your billing process, train your team, and contact HMS Group Inc for expert help in preventing CO 97 denials and improving your billing.

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