CO 29 Denial Code: Timely Filing Expired

Official CARC description: “The time limit for filing has expired.” Here’s what it actually means, why it fires, and how to get the claim paid.

Contractual Obligation (CO)Fix steps belowFree appeal letter draftNo PHI needed

What CO 29 actually means

The claim arrived after the payer's filing deadline (90–365 days depending on contract). The write-off is NOT automatic — proof of timely original submission wins these routinely.

Liability group: CO = Contractual Obligation — the provider absorbs it — the amount cannot be billed to the patient. If the denial is wrong, the money is recovered by correcting or appealing the claim, not by balance-billing.

Why CO 29 fires

How to fix CO 29

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Step 1

Pull the clearinghouse acceptance report for the ORIGINAL submission date

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Step 2

Check the contract's actual filing limit — payer reps often quote the wrong one

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Step 3

For COB delays: most contracts start the clock at the primary EOB date

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Step 4

Set a weekly rejected-claims sweep so rejections never age out silently

How to appeal it

Appeal with proof of timely filing: clearinghouse acceptance report, ANSI 277CA, certified-mail receipt, or the primary EOB date for secondaries. Most payers must accept electronic acceptance reports as proof.

Draft a CO 29 appeal letter now ↓

Draft the appeal letter

Fill in the denial facts — use placeholders, never real patient data (the letter keeps [PATIENT NAME]-style fields so you can merge real details privately). A payer-ready draft with an enclosure checklist comes back in ~20 seconds.

Your appeal letter draft will appear here.

Frequently asked questions

What does denial code CO 29 mean?

The time limit for filing has expired. In practice: The claim arrived after the payer's filing deadline (90–365 days depending on contract). The write-off is NOT automatic — proof of timely original submission wins these routinely.

Is CO 29 the provider’s write-off or the patient’s responsibility?

CO stands for Contractual Obligation — the provider absorbs it — the amount cannot be billed to the patient. If the denial is wrong, the money is recovered by correcting or appealing the claim, not by balance-billing.

Can you appeal a CO 29 denial?

Appeal with proof of timely filing: clearinghouse acceptance report, ANSI 277CA, certified-mail receipt, or the primary EOB date for secondaries. Most payers must accept electronic acceptance reports as proof.

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