How do I resolve a CO-29+N380 denial?

Pull all available electronic submission records: 277CA acknowledgment, clearinghouse batch confirmation, and any 835 remittances that reference the claim. Request a claims history report from the payer to confirm what date they first received the claim. If the payer's records show a receipt date within the filing window, appeal with side-by-side documentation of your submission date vs. the payer's stated receipt date. If there is a discrepancy, escalate to the payer's provider relations department with a request for claims history investigation. Consider filing a complaint with your state's Department of Insurance if the payer cannot produce evidence that the claim was received late.

Can I appeal a CO-29+N380 denial?

Yes. CO-29+N380 denials are typically appealable with a 22% success rate. Resolution difficulty is Hard and typically takes 30-90 days.

835 Denial Combination

CO-29+N380

Contractual Obligation · Claim-Level Adjustment

What This Combination Means

Timely filing denial — the claim was received beyond the allowed filing period, and the remark N380 indicates that proof of timely filing was not sufficient. An appeal was likely attempted but the supporting documentation did not satisfy the payer's requirements.

22%

Appeal Success

30-90 days

Avg. Resolution

Hard

Difficulty

Yes

Appealable

Step-by-Step Resolution

Steps tailored specifically to this CO-29+N380 combination — not generic advice.

1
Pull all available electronic submission records: 277CA acknowledgment, clearinghouse batch confirmation, and any 835 remittances that reference the claim.
2
Request a claims history report from the payer to confirm what date they first received the claim.
3
If the payer's records show a receipt date within the filing window, appeal with side-by-side documentation of your submission date vs. the payer's stated receipt date.
4
If there is a discrepancy, escalate to the payer's provider relations department with a request for claims history investigation.
5
Consider filing a complaint with your state's Department of Insurance if the payer cannot produce evidence that the claim was received late.

Specialty Context

How CO-29+N380 typically presents across different practice types.

Dental

Submit the clearinghouse's electronic submission confirmation (277 Acknowledgment) as proof — a screenshot of your PMS submission date alone is rarely sufficient.

Medical

For Medicare timely filing appeals, a 999 functional acknowledgment or 277CA from the clearinghouse is the gold standard. The CMS Claims Processing Manual Chapter 1 defines acceptable proof.

Behavioral Health

If the original denial was for TFL and the appeal was denied because proof was insufficient, escalate to the payer's provider dispute resolution process with all electronic transmission records.

Individual Code References

View the standalone definition for each code in this combination.

CARC 29 RARC N380

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