CO 16 is one of the most common denial codes in medical billing. It usually happens when a payer denies a claim based on a lack of information, incorrect information, or incomplete information. But the code itself cannot identify exactly what information is missing. To know the exact reason, you need to check the accompanying remark codes.
If your claim has been returned with CO 16 and you are unsure about how to handle it, don’t worry; this guide will help you understand what causes these denials and how you can fix them.
What Is the CO 16 Denial Code?
A Contractual Obligation 16 (CO 16 denial code) is a common Claim Adjustment Reason Code (CARC) that identifies missing information or a submission/billing error as the reason for the claim denial. Mostly, providers encounter this code on Electronic Remittance Advice (ERA) and Explanation of Benefits (EOB) reports.
Payers use American National Standards Institute (ANSI) accredited X12 CARC and RARC codes to provide standard explanations for claim adjustments and remittance information. CARC codes indicate the general problem, while RARC (Remittance Advice Remark Code) and NCPDP Reject Reason Code help identify more specific issues behind the denial. Without a RARC, CARC can’t help identify the exact issue.
According to X12, the CO 16 denial code description is “Claim/ services lacks information or has submission/billing error(s).” The missing or incorrect information is needed to process the claim.
According to X12, “this code can not be used for claims attachments/ other documentation. Moreover, at least one RARC remark code or NCPDP Reject Reason Code must be provided.” This means you need to check the accompanying RARC, such as N286 or N245, etc to know exactly why the claim was denied.
However, it is important to note that CO 16 isn’t a medical necessity denial or a payment reduction. In fact, it is just an administrative denial, which means the service itself isn’t being questioned. The reimbursement delay is due to missing or incorrect information and can be resolved once you correct and resubmit the claim.
Want to know about other denial codes? read Top 10 Common Denials in Medical Billing
What Causes a CO 16 Denial?
Main CO-16 denial code reasons are:
- Missing or Incorrect Patient Information: For instance, if the patient name, date of birth, ID number, or history doesn’t match the payer’s data, it can lead to a CO-16 adjustment. It could be due to incorrect data, an invalid member ID, or incomplete demographic information.
- Insurance and Eligibility Information Errors: If insurer details or the patient’s selected plan details are incorrect or outdated. For example, a patient has two active insurance plans, but the provider’s records don’t indicate which insurer is primary and which is secondary. This missing coordination of benefits (COB) information can prevent the payer from processing the claim correctly.
- Provider Information and NPI Errors: Another major reason for CO 16 adjustment is an incorrect billing or rendering provider NPI. This can happen when the provider’s identification information is missing, incorrect, invalid, or doesn’t match the payer’s records.
- Coding and Claim Submission Errors: This means the claim is not coded properly or has submission errors. It can include missing or invalid diagnosis or procedure information, incorrect modifiers, incomplete required claim fields, and incorrect claim formatting.
- Authorization and Referral Information: CO 16 can also be triggered if the claim has missing or invalid authorization details or if referral information is not included where required.
The CO 16 denial can cause delayed reimbursements, increased A/R days, claims rework, and disruptions to cash flow when denials accumulate.
How to Identify the Exact Reason Behind a CO 16 Denial
To identify the exact reason behind a CO 16 denial, you need to know two things:
- The EOB or ERA where the billing team reviews the adjustment information.
- What the RARC code is.
Common remark codes that are associated with CO-16 are:
| Remark Code | What it Indicates | What to Check |
| MA27 | It indicates a missing/incomplete/invalid entitlement number or name. | Patient’s medicare entitlement details |
| N382 | missing/ incomplete/invalid patient identifier | Patient identifier submitted on the claim |
| N286 | missing/incomplete or invalid referring provider primary identifier | Provider information |
| N245 | Incomplete or invalid plan information for other insurance | Check other insurance and COB details. |
Disclaimer: These are examples, not an exhaustive list. Always verify the exact remark code against the current official code set and payer guidance.
What If The ERA Shows CO 16 Without a Clear Explanation?
ERAs usually include RARC codes specified with the CO 16, but in case you can’t find a clear explanation, first review the full claim-level and service-line adjustment details. Next, check all of the remark codes and review the applicable 835 Healthcare Policy Identification Segment. If you still can’t find a clear explanation, contact the payer.
How to Fix a CO-16 Denial: Step-by-Step Guide
After identifying the reason for denial, the next step is to fix it. Here is a step-by-step guide on how you can fix a CO-16 denial code and prevent unnecessary delays.
Step 1: Review the EOB/ERA
The first step is to review the EOB or ERA you received from the payer. Identify CARC 16 and check the remark codes listed alongside it.
These codes provide more detail about the information the payer needs.
Also, check whether CO-16 applies to the entire claim or only a specific service line. This can help you narrow down the issue before you review the claim further.
Step 2: Identify the Missing/Incorrect Information
Once you identify the remark code, compare the patient’s record with the claim submitted. This helps you identify missing or incorrect details like name, DOB, insurance ID, insurance coverage or COB details, billing and rendering NPIs, code errors, payer info, required authorization or referral details, etc.
The RARC remark helps you narrow down the issue and identify what to correct. For example, if the payer flags a missing provider identifier, that means you only need to review the relevant provider details rather than the entire claim.
Step 3: Verify the Correct Information
Before correcting the information, review the patient’s registration information, insurance documents, and provider records. This can help you confirm the patient’s active coverage and determine whether they have multiple insurance plans.
Tip: Do not copy details from an old claim without verifying. Always make corrections based on the patient’s records and the payer’s requirements.
Step 4: Correct the Claim
Next, update the denied claim information. Make sure every correction has support in the patient’s records or other documentation.
For example, if the claim has an incorrect rendering provider NPI, verify the correct identifier and update the applicable field. If the payer requests additional information, provide it through the method specified in its instructions.
Review the corrected claim before submission. An incomplete correction can lead to another denial.
Step 5: Resubmit and Track the Claim
Lastly, follow the payer’s designated process and resubmit the corrected claim. Follow any instructions regarding the submission deadline and correction. Also, only include supporting documents when required.
Always keep a record of the resubmission date and claim reference number so you can follow up on the claim. Moreover, check the claim status until the payer processes it.
For Example
Suppose you receive a CO 16 adjustment with remark code N286. This remark points to a missing, incomplete, or invalid referring provider primary identifier.
All you need to do is review the ERA and check the original claim. If the referring provider’s identifier is missing, verify the correct details against the provider records, update the relevant claim information, and resubmit the claim according to the payer’s instructions.
Should You Submit a Corrected Claim or Appeal a CO-16 Denial?
The right next step depends on why the payer needs adjustments to the claim. Suppose you find an answer in the ERA or EOB report; simply correct and resubmit the claim. But if your information was correct and you believe it is a mistake on the payer’s end, you can request reconsideration or file an appeal.
| Corrected claim | appeal |
| Used when the submitted claim contains missing or incorrect information | Used when the provider believes the payer’s decision is incorrect |
| Requires correcting the relevant claim data | Requires supporting evidence and a dispute of the adjustment |
| Follows the payer’s corrected-claim process | Follows the payer’s appeal process |
You can also contact the payer for clarification. For example, if you find that the remark code does not clearly explain what information is missing, ask the payer for clarification.
Here, it is also important to consider the filing deadline before submitting anything. A claim correction and an appeal are not filed using the same process, so going the wrong route can cost you the deadline as well.
How to Prevent Recurring CO-16 Denials
Recurring CO 16 code denials can impact your clean submission rate and first pass rate. Moreover, they can also signal a gap in your billing process. Here are a few practical steps that can help you avoid recurring CO-16 denials:
- Strengthen your patient registration and insurance verification system. Accurately recording and verifying patients’ details before the appointment can save you time. If a patient changes plans or reports additional coverage, update the records and confirm which insurer is primary.
- Check the provider’s details before you submit the claim. Confirm that the billing and provider details match the records. Your team should also check referral and prior authorization requirements for each payer.
- Use a pre-submission claim scrubber, as it can help flag missing fields, invalid codes, and other common errors.
- Identify common denial trends in CO 16 denials and use remark codes to analyze root causes. Check whether most denials are related to payer or provider information or claim type. You can also use denial reports to improve workflows.
FAQs
What is the difference between CO and PR?
CO and PR are adjustment group codes that indicate different responsibility categories. CO stands for Contractual Obligation, while PR stands for Patient Responsibility.
To learn more, read: Denial Management in Medical Billing.
Is CO 16 a denial or a rejection?
CO 16 is a claim adjustment reason code that appears on a payer’s remittance advice. A clearinghouse rejection occurs before the payer completes claim adjudication, often because the claim fails an initial validation check.
Should CO 16 be resubmitted or appealed?
The majority of CO 16 denials are meant to be resubmitted as amended claims. An appeal is only suitable when the original claim was correct and complete, and the payer refused it as an error.
Conclusion
Recurring CO 16 denial code usually means issues with front-desk, registration, enrollment, or coding. You should consider outsourcing denial management services if CO 16 remains among your top denial reasons. While looking for a partner specifically for denial management, evaluate their denial reporting by payer and remark code, document compliance practices, credentialing support, appeal and denial resolution rate, coding expertise, root cause analysis, and reporting capabilities.
Zee Medical Billing provides end-to-end medical billing services, along with denial management, credentialing, coding, and compliance support. Talk to our expert to see how we can help you.
