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CO-29CO-29 denial: what it means and how to fix it
CO-29 means the payer says the claim reached them after their filing deadline. Deadlines differ by payer and by contract, so the question is whether you can prove the claim was received in time, or that the delay had a reason the payer accepts.
Common causes
- The claim was first sent after the payer's filing window had already closed
- The claim was sent on time but rejected by the clearinghouse or payer, and the corrected version went out after the deadline
- The claim went to the wrong payer first (for example, coverage changed or the patient had another primary plan), and it reached the right payer too late
- The payer is counting from a different date than you are, such as the date of service instead of the date the primary payer processed the claim
How to fix it
- Check the payer's filing deadline in your contract or their provider manual, and confirm which date they count from
- Look for proof the claim was received in time: a clearinghouse acceptance report or a payer acknowledgment, not just a report that it left your system
- If you have that proof, appeal or request reconsideration with the proof attached, following the payer's process
- If the delay came from something outside your control, such as retroactive eligibility or waiting on the primary payer's decision, include the document that shows when you learned of it
- If the claim truly went out late with no accepted reason, it usually can't be billed to the patient under a CO denial; check your contract and adjust it off, then review why it was late to prevent repeats
General guidance only. Payer rules vary, so always check the payer's policy.
See the official X12 description