Receiving a CO 27 denial code can delay reimbursement and create unnecessary work for your billing team, but the reason behind it is usually straightforward. This denial indicates that the expenses were incurred after the patient’s insurance coverage had terminated, which means the coverage dates and date of service need immediate attention. However, a terminated policy does not always mean the claim is unrecoverable.
Outdated insurance information, eligibility errors, a change in health plans, or incorrect payer records can also contribute to the denial. By identifying the actual cause and taking the right corrective action, healthcare providers can recover eligible payments and reduce repeat denials.
In this article, we’ll explain what CO 27 denial code means, why it occurs, how to resolve it, and what your billing team can do to prevent it from disrupting your revenue cycle.
What Is the CO 27 Denial Code?
The CO 27 denial code indicates that the expenses associated with a claim were incurred after the patient’s insurance coverage had terminated. The official description for Claim Adjustment Reason Code (CARC) 27 is “Expenses incurred after coverage terminated.”
In practical terms, the insurance payer is indicating that the patient’s policy was no longer active when the healthcare service was provided. For example, if a patient’s insurance coverage terminated on June 30 but the date of service was July 10, a claim submitted to that insurance plan may be denied with reason code 27.
However, healthcare providers should not automatically assume that every CO 27 denial is correct. Eligibility information can change, payer records can contain discrepancies, patients can switch insurance plans, and coverage can sometimes be updated retroactively. Billing teams should investigate the claim before determining the appropriate next step.
What Does “Expenses Incurred After Coverage Terminated” Mean?
The phrase “expenses incurred after coverage terminated” means the payer believes the healthcare services were provided after the patient’s insurance policy had ended.
Consider a simple example:
A patient has health insurance coverage through an employer until March 31. The patient receives medical services on April 8, but the provider submits the claim to the previous insurance company. Since that policy was no longer active on April 8, the payer may process the claim with denial reason code 27.
This makes the date of service and insurance coverage dates critical when investigating the denial.
The billing team should verify when coverage actually ended and whether another insurance plan was active on the date of service. If the patient had valid coverage or the payer’s termination information is incorrect, further investigation or an appeal may be appropriate.
What Causes CO 27 Denial Code?
Understanding the root cause of a CO 27 denial is essential because simply resubmitting the same claim without correcting the underlying issue can result in another denial. Several situations can trigger this code.
Insurance Coverage Terminated Before the Date of Service
This is one of the most straightforward causes. The patient’s policy may have ended before the healthcare service was provided.
Coverage can terminate for several reasons, including a change in employment, switching insurance companies, changes in plan eligibility, or expiration of a particular policy.
If the payer confirms that coverage legitimately ended before the date of service, the billing team should determine whether another insurance plan was active at that time.
Eligibility Was Not Verified Before the Appointment
Failure to verify insurance eligibility can allow inactive coverage information to remain in the patient’s account.
If staff rely exclusively on insurance information collected during a previous visit, they may submit a claim to a policy that is no longer active. Eligibility verification before services are provided helps identify these changes earlier in the billing process.
Patient Changed Insurance Plans
Patients may change insurance because of a new employer, annual enrollment, a change in personal circumstances, or a decision to select another health plan.
If the practice does not collect the patient’s updated insurance information, the claim may be sent to the previous payer. The old insurer may then return denial code 27 because its coverage ended before the date of service.
Incorrect or Outdated Insurance Information
Incorrect information in the patient’s account can also contribute to coverage-related denials.
The billing team may have an outdated member ID, policy information, payer selection, or coverage record. Even when the patient currently has insurance, submitting the claim using obsolete coverage information can send it to the wrong plan.
Retroactive Insurance Termination
In some cases, an insurance company may update a member’s eligibility information after services have already been provided.
This can create a challenging situation because the provider may have verified coverage when the patient arrived, only to discover later that the payer shows the policy as terminated for that date.
When this happens, billing staff should review available eligibility records and contact the payer when necessary to determine the correct coverage status.
Coverage Changed Between Scheduling and the Date of Service
Verifying benefits when an appointment is scheduled is useful, but it may not be sufficient if the appointment takes place weeks or months later.
A patient’s insurance can change during that period. Rechecking eligibility close to the actual date of service can help identify terminated or replaced coverage before a claim is submitted.
How to Fix CO 27 Denial Code
Resolving a CO 27 denial code requires more than immediately correcting and resubmitting the claim. The first priority is determining whether the payer’s coverage information is accurate.
A structured resolution process can help billing teams avoid repeated submissions and determine the correct payer or responsible party.
Step 1: Review the ERA or EOB
Start by carefully reviewing the Electronic Remittance Advice (ERA) or Explanation of Benefits (EOB) associated with the denied claim.
Check the:
- Claim Adjustment Reason Code
- Adjustment group code
- Any accompanying remark codes
- Patient information
- Member or policy information
- Date of service
- Payer information
- Billed and adjusted amounts
Do not review CARC 27 in isolation. Additional codes and remittance information may provide important context about why the payer processed the claim this way.
Step 2: Verify Eligibility for the Date of Service
Next, verify the patient’s insurance eligibility for the exact date the healthcare service was provided.
Current eligibility alone does not answer whether the patient was covered on a previous service date. The billing team needs historical eligibility information corresponding to the claim.
Check the policy’s effective and termination dates and compare them with the date of service.
Step 3: Confirm the Coverage Termination Date
If the payer indicates that coverage was terminated, determine the exact termination date.
For example, suppose the payer reports that coverage terminated on August 31 while the service was provided on September 5. In that situation, the service falls outside the coverage period according to the payer’s records.
If your records indicate that coverage was active on September 5, however, investigate the discrepancy rather than simply writing off or transferring the balance.
Step 4: Check for Another Active Insurance Plan
Patients frequently obtain new insurance after their previous coverage ends.
Contact the patient or review available eligibility information to determine whether another health plan covered the patient on the date of service.
If another payer was responsible, verify:
- New insurance carrier
- Member ID
- Effective date
- Plan details
- Primary and secondary coverage
- Coordination of benefits, when applicable
The claim can then be prepared for the appropriate payer according to billing and timely filing requirements.
Step 5: Correct and Resubmit the Claim When Appropriate
If the investigation reveals that the claim was originally sent using incorrect or outdated insurance information, correct the patient’s coverage details.
Before submitting the corrected claim, verify that all relevant information is accurate. Repeatedly sending a claim without addressing the original problem can waste staff time and extend the reimbursement cycle.
Also review the new payer’s timely filing requirements. If the claim is approaching or has passed a filing deadline, supporting documentation may be necessary depending on the payer’s policies.
Step 6: Appeal When Coverage Was Active
A CO 27 denial does not necessarily mean the claim should always be redirected or closed.
If eligibility records demonstrate that the patient had active coverage on the date of service, contact the payer to investigate. If required, submit a reconsideration or appeal according to the payer’s procedures.
Supporting documentation may include:
- Eligibility verification records
- Coverage confirmation
- Patient insurance documentation
- Original claim information
- Relevant payer correspondence
The goal is to demonstrate that the patient had valid coverage when the service was rendered.
Step 7: Determine the Correct Financial Responsibility
If the patient truly did not have coverage on the date of service and no other insurance applies, the billing team must determine how the remaining balance should be handled.
Do not assume that CARC 27 alone determines patient responsibility.
Review the adjustment group code, ERA/EOB details, payer contract, plan requirements, applicable regulations, and organizational billing policies before transferring a balance to the patient or making an adjustment.
CO 27 vs. PR 27: What’s the Difference?
One common source of confusion is the difference between CO 27 and PR 27.
The number 27 represents the Claim Adjustment Reason Code associated with expenses incurred after coverage terminated. The letters preceding the number are adjustment group codes that provide additional context regarding financial responsibility.
| Code | Meaning | Key Action |
| CO 27 | CARC 27 reported under the Contractual Obligation group | Review payer processing, eligibility, contract terms, and remittance details |
| PR 27 | CARC 27 reported under the Patient Responsibility group | Verify eligibility and review payer information before determining the appropriate patient balance |
This distinction matters because billing teams should not make financial decisions based solely on the reason code number.
The entire remittance should be reviewed, including the group code, CARC, applicable remark codes, payer instructions, and contractual requirements.
CO 27 Denial Code Resolution Checklist
When your billing team receives a CO 27 denial, use this checklist to keep the resolution process focused:
- Review the ERA or EOB and identify all relevant adjustment and remark codes.
- Confirm the date of service on the denied claim.
- Verify historical eligibility for that exact service date.
- Compare the effective and termination dates with the date of service.
- Confirm the patient’s insurance information for accuracy.
- Check for another active insurance plan on the date of service.
- Correct the claim and submit it to the appropriate payer when necessary.
- Contact or appeal to the payer when evidence indicates coverage was active.
- Review timely filing requirements before resubmitting or redirecting the claim.
- Document the outcome and update the patient record to help prevent the same issue from recurring.
A consistent checklist helps billing staff move from simply reacting to denials toward identifying and correcting their underlying causes.
How Denial Management Services Can Help Reduce CO 27 Denials
Managing CO 27 and other recurring denials can consume valuable staff time, especially when teams are already balancing claim submission, payment posting, appeals, and follow-ups. Professional denial management services from Health Med Affairs can help healthcare organizations investigate root causes, prioritize recoverable claims, correct billing issues, manage payer follow-ups, and identify patterns contributing to lost or delayed revenue.
More importantly, denial management should not focus only on recovering claims after they are denied. Analyzing recurring eligibility and coverage issues can reveal weaknesses in registration, insurance verification, and claim submission workflows.
Addressing those weaknesses can help providers reduce preventable denials, improve clean claim performance, and maintain a more predictable revenue cycle.
Summary
The CO 27 denial code indicates that the payer believes the expenses were incurred after the patient’s insurance coverage terminated. While the explanation appears simple, resolving the denial requires careful verification of the date of service, coverage dates, insurance information, adjustment codes, and any alternative coverage available to the patient.
Healthcare providers can reduce these denials by strengthening eligibility verification, confirming insurance information at each visit, training front-end teams, and monitoring recurring denial patterns. When a CO 27 denial does occur, a structured investigation helps determine whether the claim should be corrected, submitted to another payer, appealed, or handled according to the applicable financial responsibility requirements.
By combining effective denial resolution with stronger front-end processes, healthcare organizations can reduce avoidable claim delays, protect revenue, and build a more efficient revenue cycle.
