Denial codes / CO-29
CO-29 denial: meaning, fix & appeal letter template
Payer says the claim arrived after the filing deadline.
What it means
Official CARC 29 descriptionThe time limit for filing has expired.
The payer received the claim after its timely-filing limit (often 90–180 days for commercial plans, 12 months for Medicare). These are winnable only with proof the claim was filed on time or a valid reason for delay.
Common causes
- Original claim rejected at the clearinghouse and never resubmitted
- Payer lost or mis-posted the original submission
- Claim sent to the wrong payer first (eligibility or COB issue)
- Late primary EOB delayed the secondary claim
- Corrected claim treated as a new claim and date-stamped late
How to fix it
- Pull the clearinghouse acceptance report (999/277CA) for the original submission
- Check the payer contract for the exact timely-filing limit and exceptions
- Gather proof of good cause (retro-eligibility, other payer's denial date)
- Appeal with proof of timely filing — before the appeal window closes
- Monitor clearinghouse rejections daily so this doesn't recur
Appeal or corrected claim?
Appeal — with proof. CO-29 is not fixable by a corrected claim. Appeal only if you can show the claim was filed on time (payer acceptance report, not just your PM system's send log) or that a contract exception applies. Without proof, this is usually a write-off.
What to attach
- Clearinghouse acceptance report (999/277CA) with payer-accepted date
- Original claim copy and claim history
- Other payer denial / retro-eligibility letter (for good-cause exceptions)
- Payer contract timely-filing clause
CO-29 appeal letter template
Replace every [BRACKETED] field. Remove any optional paragraph that doesn't apply.
[PRACTICE NAME] [ADDRESS] · [PHONE] · NPI [NPI] · TIN [TIN] [DATE] [PAYER NAME] Attn: Appeals / Provider Disputes [PAYER APPEALS ADDRESS] Re: Request for Reconsideration — Claim [CLAIM NUMBER] Patient: [PATIENT NAME] Member ID: [MEMBER ID] DOB: [DOB] Date of Service: [DOS] CPT: [CPT CODE] Billed: [AMOUNT] Denial: CO-29 — The time limit for filing has expired. Dear Appeals Reviewer, We request reconsideration of the denial of the above claim. The above claim was denied with CARC 29, indicating the time limit for filing has expired. The claim was originally submitted on [ORIGINAL SUBMISSION DATE], within the [NUMBER]-day timely-filing limit for this plan. The enclosed clearinghouse acceptance report ([999/277CA], control number [NUMBER]) shows the claim was accepted by [PAYER NAME] on [ACCEPTANCE DATE]. [If applicable: the delay was caused by [REASON — e.g. retroactive eligibility granted on [DATE]], which qualifies under [CONTRACT SECTION / POLICY].] Based on the enclosed documentation, we request that [PAYER NAME] overturn this denial and reprocess the claim for payment in accordance with the member's benefits and our participation agreement. Enclosures: - Clearinghouse acceptance report (999/277CA) with payer-accepted date - Original claim copy and claim history - Other payer denial / retro-eligibility letter (for good-cause exceptions) - Payer contract timely-filing clause Please contact [CONTACT NAME] at [PHONE] or [EMAIL] with any questions. Sincerely, [NAME], [TITLE] [PRACTICE NAME]
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