Denial Code Decoder
CO-29 — Filed after the timely filing limit
The claim arrived after the payer's filing deadline. This is one of the least forgiving denials — most payers only overturn it with PROOF the claim was originally submitted on time, not with an explanation of why it was late.
Billable to the patient? Almost never — most contracts and many state rules forbid billing the patient for a provider's late filing.
Where this denial is born
- Front desk
- Coding
- Claim build
- Submission
- Adjudication
This denial is usually created at the highlighted stage — that is where prevention lives.
Answer the questions — follow the path
The same questions an experienced biller asks, in order. Your answers draw the route to the right action.
Do you have proof of a timely original submission?
A clearinghouse acceptance report or payer acknowledgment showing a date inside the limit.
The full decision tree
Do you have proof of a timely original submission?
A clearinghouse acceptance report or payer acknowledgment showing a date inside the limit.
- Yes →
Appeal with the submission evidence. File the appeal with the acceptance report attached. This is the strongest appeal in the denial world — payers routinely overturn CO-29 against hard proof.
- No →
Is there a qualifying reason the clock should not apply?
Retroactive eligibility, incorrect COB information from the payer, or a payer-side error can reset the limit.
- Yes →
Appeal on the exception. Document the qualifying circumstance (retro eligibility letter, payer correspondence) and appeal citing the payer's own exception policy.
- No →
Write off — and fix the leak. Without evidence or an exception this claim is lost. The real work is upstream: find which queue let it age past the limit and put an aging alarm on it.
- Yes →
Prevention
Preserve acceptance reports and clearinghouse acknowledgments for every batch — timely filing appeals are won with evidence captured on the day of submission, not reconstructed later.
Related reading
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