CO-29 denials are almost always overturnable with proof of timely submission. The key is documentation — submission logs, clearinghouse reports, or payer acknowledgment records.
Best proof: 277 acceptance report + clearinghouse timestamp showing submission within window.
Primary payer processed late; secondary timely filing clock should run from primary EOB date.
Payer rejected or lost the original claim. Document the rejection reason and resubmission date.
Patient coverage confirmed retroactively after DOS; timely filing clock runs from eligibility confirmation date.
TODAY'S DATE
PAYER NAME
Claims Appeals Department
PAYER ADDRESS OR FAX
RE: Timely Filing Appeal — Request for Claim Reconsideration
Patient: PATIENT FULL NAME
Member ID: MEMBER ID
Date of Birth: MM/DD/YYYY
Claim Number: CLAIM NUMBER (if assigned)
Date(s) of Service: DOS
Procedure Code(s): CPT CODES
Billed Amount: $AMOUNT
Denial Code: CO-29 or applicable code
Denial Date: DATE
Dear Claims Appeals Department,
We are writing to appeal the denial of the above-referenced claim for timely filing. The claim was denied with reason code CO-29 / denial code, stating the claim was not received within the required filing period.
We respectfully submit that this claim was submitted timely and request reconsideration based on the following:
Proof of Timely Submission:
SELECT THE APPLICABLE SCENARIO AND DELETE THE OTHERS:
Option A — Clearinghouse submission:
The claim was originally submitted to PAYER NAME via CLEARINGHOUSE NAME — e.g., Availity, Change Healthcare, Waystar on ORIGINAL SUBMISSION DATE — within the required X-day filing window from the date of service (DOS). Enclosed is the clearinghouse submission report confirming receipt and the 277CA acceptance acknowledgment dated DATE.
Option B — Coordination of Benefits delay:
This claim was subject to coordination of benefits. The primary payer, PRIMARY PAYER NAME, processed the claim and issued an EOB on PRIMARY EOB DATE. Per standard COB guidelines and PAYER NAME's own coordination of benefits policy, the secondary filing deadline runs from the date of the primary payer's determination — not the date of service. The claim was submitted to PAYER NAME on SECONDARY SUBMISSION DATE, within X days of the primary EOB. A copy of the primary EOB is enclosed.
Option C — Payer system error / claim lost:
The original claim was submitted on ORIGINAL SUBMISSION DATE but was rejected / not processed due to REASON — e.g., "an eligibility mismatch caused by incorrect member ID on file at the time of service". Upon discovering the rejection on DATE DISCOVERED, we corrected and resubmitted the claim on RESUBMISSION DATE. The original submission is documented by PROOF — clearinghouse report / payer rejection notice enclosed herein. The delay was caused by PAYER / SYSTEM ERROR and not by the provider.
Option D — Retroactive eligibility:
The patient's insurance coverage was confirmed retroactively on DATE ELIGIBILITY CONFIRMED. At the time of service (DOS), the patient's active coverage under PAYER NAME was not verifiable. Upon receiving confirmation of retroactive enrollment, we submitted the claim on SUBMISSION DATE, within X days of the eligibility notification. Documentation of the retroactive eligibility confirmation is enclosed.
Supporting Documentation Enclosed:
We respectfully request that this claim be reconsidered and processed for payment. The total billed amount is $AMOUNT.
Sincerely,
SIGNATORY NAME
TITLE
PROVIDER / FACILITY NAME
PHONE | EMAIL
Timely filing windows vary by contract. Search Axlow for your payer's administrative guidelines to confirm the window before you appeal — and cite it in your letter.