What does CO-29 mean?
CARC code 29 is a timely filing denial. The payer is saying you submitted the claim after their filing deadline (typically 90-365 days depending on the payer). This is very difficult to overturn unless you have proof that the original claim was submitted on time. Gather your clearinghouse submission receipts, EDI acknowledgments, or tracking numbers that show the claim was received within the filing window. Without proof of timely submission, the overturn rate is only about 10%. Always save your clearinghouse submission confirmations.
How to appeal CO-29
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
Only appeal with proof of timely original submission — clearinghouse receipt or tracking number.