CO-78: Non-Covered Days / Room Charge Adjustment
Non-covered days are a contractual write-off. Appeal with clinical documentation if the days were medically necessary; otherwise post the adjustment.
What Does CO-78 Mean?
CO-78 designates the non-covered days as a contractual write-off. The payer determined that specific dates did not meet coverage criteria — most commonly due to a retrospective level-of-care downgrade, authorization lapse, or contractual day limit. The provider cannot bill the patient for these days and must absorb the cost unless the denial is overturned on appeal.
When CARC 78 appears on a remittance, the payer is telling you that certain hospital days or room charges fall outside the scope of coverage. This is not a blanket claim denial — the payer may have paid for part of the stay and is adjusting specific dates that it considers non-covered.
The reasons behind CARC 78 vary significantly depending on the group code. Under CO, the non-covered days typically result from a payer's retrospective determination that the patient no longer met inpatient criteria on those dates, that the stay exceeded a contractual day limit, or that prior authorization lapsed before the patient was discharged. These are among the most frequently appealed inpatient adjustments because they often hinge on clinical judgment about medical necessity.
Under PR, the picture changes: the patient has exhausted their covered benefit days. For Medicare patients, this means all 90 standard days plus 60 lifetime reserve days per benefit period have been used. For commercial plans, it means the annual or per-admission day limit has been reached. PR-78 shifts the financial burden directly to the patient. The provider should verify the benefit day count, check for secondary coverage, and issue an Advance Beneficiary Notice if the exhaustion was foreseeable.
OA-78 appears less frequently, primarily in coordination of benefits scenarios. Tracking CARC 78 patterns by payer and service line helps identify systemic issues with authorization management, utilization review timing, or discharge planning.
Common Causes
| Cause | Frequency |
|---|---|
| Patient stay exceeds maximum covered days under contract The patient's inpatient stay extended beyond the maximum number of days covered under the provider's contract with the payer, and the contractual terms prohibit billing the patient for the excess days | Most Common |
| Level of care downgrade by payer The payer determined the patient no longer met inpatient criteria during the stay and retroactively downgraded the level of care, making the remaining days non-covered at the billed room rate | Most Common |
| Missing or expired prior authorization for continued stay The required authorization for the inpatient stay was not obtained or expired during the admission, and the payer denied coverage for days beyond the authorized period | Common |
| Insufficient medical necessity documentation for continued stay Clinical documentation did not adequately support the medical necessity of continued inpatient care for the denied days | Common |
| Retroactive denial after concurrent review The payer initially approved the admission but reversed the approval after reviewing clinical documentation, making previously covered days non-covered | Occasional |
How to Resolve
Identify which days were denied and why, verify the denial basis against coverage terms, then write off, appeal with clinical documentation, or bill the patient.
- Determine the denial reason Check RARCs to understand whether the denial is based on medical necessity, level of care, authorization, or contractual day limits. Each requires a different response strategy.
- Assess appeal viability Review clinical documentation for the denied dates. If the record supports inpatient-level care, gather physician attestation, nursing notes, and test results to build an appeal.
- File a clinical appeal if warranted Submit a peer-to-peer review request or formal appeal with detailed medical records, a letter from the attending physician, and a clinical summary explaining why inpatient care was necessary on each denied date.
- Post the write-off if the denial is valid If the contract supports the non-covered day determination and the documentation does not justify an appeal, post the CO-78 adjustment as a contractual allowance.
Common RARC Pairings
The RARC code tells you exactly what triggered the CO-78:
| RARC | Description |
|---|---|
| N362 | Alert: The number of days exceeds the payer's maximum allowance for this type of service. |
| N386 | Alert: This decision was based on a review of medical records or clinical criteria. |
| MA04 | Alert: Secondary payer cannot calculate benefits without the primary payer's Explanation of Benefits. |
How to Prevent CO-78
- Implement concurrent utilization review that tracks authorized days in real time and alerts case managers before coverage expires
- Obtain timely prior authorization extensions when clinical necessity supports continued inpatient care
- Ensure clinical documentation clearly supports inpatient-level criteria for every day of the stay, especially when length of stay exceeds the DRG norm
- Train case managers on payer-specific medical necessity criteria and level-of-care thresholds
- Establish discharge planning workflows that proactively transition patients when inpatient criteria are no longer met
General Prevention
- Implement concurrent utilization review to track authorized days and flag cases approaching coverage limits
- Obtain and maintain prior authorization for inpatient stays, including extensions when clinically indicated
- Ensure clinical documentation supports continued inpatient-level care throughout the entire admission
- Train case managers on payer-specific criteria for medical necessity and level-of-care determinations
- Establish discharge planning protocols that facilitate timely transitions when inpatient criteria are no longer met
Also Filed As
The same CARC 78 may appear with different Group Codes:
Related Denial Codes
Sources
- https://www.mdclarity.com/denial-code/78
- https://ambci.org/medical-billing-and-coding-certification-blog/guide-to-claim-adjustment-reason-codes-carcs
- https://www.adonis.io/resources/denial-codes-in-medical-billing
- Codes maintained by X12. Visit x12.org for official definitions.