CO-29 Denial Code: Timely Filing Limit Expired
The CO-29 denial code means the claim arrived after the payer's timely filing deadline - the window each payer allows between the date of service and claim submission. Medicare allows 12 months from the date of service; commercial payers commonly allow anywhere from 90 days to a year, set by contract. Because the money is a provider write-off unless you can prove timely submission or qualify for an exception, prevention matters more than cure for this denial.
Common Causes
- The claim genuinely was not submitted before the deadline - held in a work queue, missing information, or lost between clearinghouse and payer
- The claim was originally rejected (not denied) at the front end and never successfully resubmitted within the window
- COB churn: waiting on a primary payer's decision consumed the secondary payer's filing window
- Insurance discovered late - the patient provided coverage information months after the visit
- The claim was filed on time but the payer has no record of receiving it
How to Fix CO-29
- Gather proof of timely filing: clearinghouse acceptance reports, electronic submission logs, or certified mail records showing the original submission date
- Appeal with that proof - most payers will overturn CO-29 when you can document a timely original submission
- For claims delayed by primary payer processing, appeal with the primary remittance date; many contracts run the secondary filing clock from the primary's adjudication
- Check the payer contract for exceptions (retroactive eligibility, newborn enrollment, misdirected claims) and cite the applicable one
- Going forward, work rejection reports daily and set filing-deadline alarms in the billing system well before each payer's limit
Frequently Asked Questions
CO-29 means the time limit for filing the claim has expired - the payer received it after their timely filing deadline. Medicare's limit is 12 months from the date of service; commercial limits vary by contract and can be as short as 90 days.
Yes, if you can prove the claim was originally submitted on time. Clearinghouse acceptance reports and electronic submission logs are the strongest evidence. Payers also grant exceptions for situations like retroactive eligibility or claims delayed by a primary payer's processing.
Generally no. CO-29 is a contractual obligation denial - filing on time was the provider's responsibility, so the balance is written off rather than shifted to the patient in most payer contracts and under Medicare rules.
Related Denial Codes
Related Resources
Claim adjustment reason codes and remittance advice remark codes are standardized code sets maintained by X12. The explanations on this page are written in our own words for educational purposes, based on public CMS and Medicare contractor documentation. Payer policies vary - always confirm handling with the specific payer's guidance and your contracts.