Timely filing limit expired
The claim arrived after the payer's deadline for filing claims. The payer will not pay and the patient cannot be billed.
CO = Contractual Obligation. The provider owes the difference. The patient cannot be billed for this amount. The same reason code can appear with a different group code; the group decides who may be billed.
Usual causes
- Claim never sent, or sent and rejected at the clearinghouse without anyone noticing.
- Secondary claim held while waiting for the primary.
- Patient gave the wrong insurance and the right payer was found late.
The fix
Find proof the claim was first sent on time: clearinghouse acceptance report, 277CA, or the first payer's remittance. Appeal with that proof. If there is no proof, write it off and fix the process: work rejections daily and track unpaid claims at 30 days.
Appeal or corrected claim?
Appeal with proof of timely submission. A corrected claim will be denied again. Some payers accept a late claim when the patient gave wrong insurance information; attach the other payer's denial.
Deadline to watch
Typical limits: Medicare 12 months from the date of service; Medicaid 90 days to 12 months by state; commercial 90 to 180 days per contract. Appeal windows are usually 60 to 180 days from the denial.
Exact limits are in your payer contract or provider manual. When in doubt, send the correction or appeal this week.
Often seen together
Timely filing expired and the payer says the decision cannot be appealed. Only proof of an earlier timely submission will reopen it.
CO-29 in short
What does CO-29 mean?
The claim arrived after the payer's deadline for filing claims. The payer will not pay and the patient cannot be billed. The official X12 text reads: "The time limit for filing has expired."
What usually causes a CO-29 denial?
Claim never sent, or sent and rejected at the clearinghouse without anyone noticing. Secondary claim held while waiting for the primary. Patient gave the wrong insurance and the right payer was found late.
How do I fix CO-29?
Find proof the claim was first sent on time: clearinghouse acceptance report, 277CA, or the first payer's remittance. Appeal with that proof. If there is no proof, write it off and fix the process: work rejections daily and track unpaid claims at 30 days.
Should I appeal CO-29 or send a corrected claim?
Appeal. Appeal with proof of timely submission. A corrected claim will be denied again. Some payers accept a late claim when the patient gave wrong insurance information; attach the other payer's denial.
What deadline applies to CO-29?
Typical limits: Medicare 12 months from the date of service; Medicaid 90 days to 12 months by state; commercial 90 to 180 days per contract. Appeal windows are usually 60 to 180 days from the denial.