What does CO-27 mean?
CARC code 27 means the patient's insurance coverage had ended before the date of service. This is one of the hardest denials to overturn because if the patient truly had no coverage, the payer has no obligation to pay. However, check for retroactive eligibility reinstatement, COBRA continuation, or state continuation coverage. If the date of service was very close to the coverage end date, you may be able to argue the information was not available at the time of service. Overall overturn rate is only about 15%.
How to appeal CO-27
Check the RARC code
The RARC (Remittance Advice Remark Code) on your ERA provides specific details about why the claim was denied. This tells you exactly what needs to be fixed.
Gather clinical documentation
Compile clinical notes, treatment plans, and any relevant guidelines that support the medical necessity of the service provided.
Submit a formal appeal letter
Write a detailed appeal letter that references clinical guidelines, payer policies, and includes supporting documentation. Submit via the payer's preferred method (fax, portal, or mail).
Key notes for behavioral health
Check for retroactive coverage or COBRA. Low overturn unless DOS was near coverage end date.