CO-A6: Prior Hospitalization or 30-Day Transfer Requirement Not Met
CO-A6 means the prior hospitalization or transfer requirement was not met. Appeal with discharge summary and admission records proving the qualifying stay occurred.
What Does CO-A6 Mean?
When paired with Group Code CO, the prior hospitalization requirement denial is a contractual adjustment. The provider absorbs the cost and cannot transfer it to the patient. Appeal with documentation of the qualifying prior stay if it occurred.
CARC A6 indicates the payer denied the claim because a required prior hospitalization or 30-day transfer condition was not met. Certain services — most commonly skilled nursing facility (SNF) admissions under Medicare — require the patient to have had a qualifying inpatient hospital stay within a specified period (typically 30 days) before the current admission or service.
The denial may occur because no qualifying prior hospitalization was found in the payer's records, the prior stay was outside the required time window, the patient was not formally transferred from a qualifying facility, documentation of the qualifying stay was not included with the claim, or incorrect admission dates prevented the system from recognizing the qualifying stay.
The most common resolution path is locating documentation of the qualifying prior hospitalization and submitting it with an appeal. If the prior stay exists but was at a different facility, obtaining records from that facility may be necessary.
Common Causes
| Cause | Frequency |
|---|---|
| No qualifying prior hospitalization The claim requires a prior hospital stay within a specified period (typically 30 days) but no qualifying admission was found in the payer's records | Most Common |
| Transfer requirement not satisfied The patient was not transferred from a qualifying facility within the required timeframe for the billed service to be covered | Most Common |
| Prior stay outside required window The patient had a prior hospitalization but the discharge date exceeds the 30-day window required for coverage of the subsequent admission | Common |
| Missing documentation of prior stay Documentation of the qualifying prior hospitalization or transfer was not included with the claim or available in the payer's records | Common |
| Incorrect admission dates The admission or discharge dates on the claim do not support the prior hospitalization or transfer requirement | Common |
How to Resolve
- Check for qualifying prior stay Review the patient's records for evidence of a prior hospitalization within the required window.
- Verify dates Confirm admission and discharge dates of the qualifying stay fall within the required timeframe.
- Obtain transfer documentation Get records from the referring facility if the prior stay was at a different hospital.
- Appeal with documentation Submit an appeal with admission records, discharge summary, transfer forms, and dates. For Medicare, file within 120 days.
- Review exceptions if requirement not met If no qualifying stay occurred, check for applicable exceptions or waivers.
Appeal with comprehensive documentation of the qualifying prior hospitalization or transfer, including admission records, discharge summary, transfer forms, and dates. Demonstrate that the prior stay falls within the required timeframe. For Medicare, file the redetermination within 120 days.
Common RARC Pairings
The RARC code tells you exactly what triggered the CO-A6:
| RARC | Description |
|---|---|
| MA130 | Your claim contains incomplete and/or invalid information. Review the claim for missing prior hospitalization documentation or incorrect dates → |
| N130 | Alert: You may need to review plan documents or guidelines. Check payer guidelines for the specific prior hospitalization or transfer requirements → |
How to Prevent CO-A6
- Verify prior hospitalization or transfer status before admitting patients for services that require it
- Obtain and document transfer paperwork from referring facilities at time of admission
- Implement admission protocols that check payer-specific prior stay requirements
- Maintain clear inter-facility communication channels for transfer documentation
- Train admissions staff on payer requirements for prior hospitalization within coverage windows
Also Filed As
The same CARC A6 may appear with different Group Codes:
Related Denial Codes
Sources
- https://x12.org/codes/claim-adjustment-reason-codes
- https://www.mdclarity.com/denial-code/a6
- https://www.cms.gov/medicare/payment/prospective-payment-systems
- Codes maintained by X12. Visit x12.org for official definitions.