CO-29 Timely Filing Denials: Build the Proof Before You Appeal
CO-29 means the payer says the filing deadline has expired. The denial is decided by dates and evidence: when the filing period began, what deadline applied, when the claim first reached the payer, and whether an exception or corrected-claim rule changes the result.
Do not use the date someone created the claim as proof of timely filing. A practice needs evidence that the payer or its designated clearinghouse accepted the submission. A local batch report can show intent, but an acknowledgement, payer acceptance report, portal history, or claim-control number is stronger evidence.
Build a filing timeline
- Confirm the correct payer and product for the date of service.
- Find the contractual or published filing limit.
- Identify the event that starts the clock, usually the date of service or discharge date.
- Find the first accepted submission and its acknowledgement.
- Record rejections, corrections, payer transfers, and replacement claims in order.
- Check whether retroactive eligibility, coordination of benefits, or payer error creates an exception.
Separate a clearinghouse rejection from a payer denial. A rejected transaction may never enter the payer's adjudication system, so the payer may not treat it as received. The rejection still matters because it shows when the practice tried to file and why the transaction failed, but the payer's contract controls whether that attempt preserves timely filing.
What an appeal should contain
Lead with a short timeline. Attach the acceptance report or acknowledgement, the payer claim-control number, relevant eligibility or coordination-of-benefits evidence, and the corrected-claim history. Point to the exact filing rule or exception. A stack of screenshots without a written chronology makes the reviewer reconstruct the account.
If no timely submission exists and no exception applies, an appeal may not be justified. Route the balance according to the contract and practice policy instead of repeatedly resubmitting it.
Prevent the next CO-29
Track unbilled encounters, clearinghouse rejections, and claims without payer acceptance separately. Age each queue from the earliest applicable filing deadline, not from the day staff last touched it. Escalate claims before they enter the final filing window and retain acknowledgement files in a searchable archive.