CO-29: Timely filing expired
Triage: Write off, appeal only with proof
By Dr. Daniel Turner, DC · Reviewed September 2, 2026
What does denial code CO-29 mean?
The claim arrived after the payer filing deadline, which can be as short as 90 days from the date of service.
What does CO-29 usually mean in a chiropractic office?
These usually trace to claims that sat in a rejected or draft state nobody was watching, or to a payer change discovered months late. The denial itself is rarely winnable; the fix is upstream.
How do you fix a CO-29 denial?
- Appeal only if you can prove the payer received the original claim in time, for example a clearinghouse acceptance report.
- Otherwise write it off. Patients cannot be billed for your timely filing miss.
- Fix the leak: work rejections weekly and watch claims that never got a response.
What this looks like in practice
A claim rejects at the clearinghouse in January for a bad member ID. The rejection report goes unread. In September someone finally notices the unpaid visit, fixes the ID, and submits a clean claim, which now denies CO-29 because the payer filing window closed months earlier. The claim was never late; the follow up was.
What the authorities say
Medicare requires claims to be filed within one calendar year of the date of service, per the Claims Processing Manual, Chapter 1, section 70. Many commercial contracts allow far less, sometimes 90 days.
How to stop it from happening again
- ✓Work clearinghouse rejections weekly; a rejected claim never started its filing clock
- ✓Age every submitted claim and chase anything without a payer response inside 30 days
- ✓Know each payer filing window and treat 90 day payers as urgent by default
Appeal language that works for CO-29
A starting paragraph in the wording reviewers expect. Replace the bracketed pieces with the claim's own facts and attach the records it references.
How Cervica handles CO-29
Cervica ages every claim from submission and surfaces claims stuck without a payer response long before deadlines pass, which is how CO-29 becomes rare instead of routine.
Quick answers
What does denial code CO-29 mean?
The claim arrived after the payer filing deadline, which can be as short as 90 days from the date of service.
What does CO-29 usually mean in a chiropractic office?
These usually trace to claims that sat in a rejected or draft state nobody was watching, or to a payer change discovered months late. The denial itself is rarely winnable; the fix is upstream.
How do you fix a CO-29 denial?
Appeal only if you can prove the payer received the original claim in time, for example a clearinghouse acceptance report. Otherwise write it off. Patients cannot be billed for your timely filing miss. Fix the leak: work rejections weekly and watch claims that never got a response.
References
General information for billing teams, not legal or payer specific advice. CARC definitions belong to X12; payer policies vary and control. Verify against the payer contract before acting on any individual claim.