CO-29 denial code
The time limit for filing has expired
How to fix it
Appeal only if you can document timely original submission — a clearinghouse acceptance report is the strongest evidence. Otherwise the revenue is lost.
How to prevent it
Work AR by filing deadline proximity, not just by balance. This denial is permanent and entirely preventable.
The CO prefix marks this a contractual obligation. The balance is absorbed by the provider under the payer agreement and cannot be transferred to the patient.
In practice
A claim for a service performed fourteen months earlier is submitted after being discovered in an unworked queue. It returns CO-29 — the filing deadline has expired. The payer's limit was twelve months from the date of service.
There is no clinical or coding defect. The service was provided, documented and correctly coded. The revenue is lost because of elapsed time alone.
The only appeal that succeeds is one demonstrating the claim was originally filed within the deadline. A clearinghouse acceptance report showing the original submission date is the strongest evidence available; a note in the practice management system that someone believes it was sent is not.
What sits behind it
Timely filing is the most permanent denial category in revenue cycle management. Almost every other denial has a path to payment through correction or appeal. This one generally does not, which makes prevention the only meaningful control.
Deadlines vary widely — commonly ninety days to a year from the date of service, and shorter for some commercial plans and some secondary filings. They also run from different starting points depending on payer and claim type, which is why a single internal deadline applied to all payers reliably misses some.
The operational implication is that accounts receivable should be worked by proximity to filing deadline, not only by balance. A large claim with six months remaining is less urgent than a small one with three weeks, and a queue sorted by dollar value inverts that priority.
Related codes
Terms used here — Timely Filing · Days in AR · Appeal
How we handle it — AR Management · Claims Management · Denial Management
Primary sources
The rules behind CO-29, at the bodies that publish them.
- Medicare timely filing requirements (opens in a new tab)
Centers for Medicare & Medicaid Services — The one-year filing limit and the narrow exceptions to it. Commercial payers set their own, usually shorter, limits by contract.
- Medicare claims appeals process (opens in a new tab)
Centers for Medicare & Medicaid Services — The five levels of appeal, what each requires and the deadline for each. Missing a level's deadline ends the appeal regardless of the claim's merits.
Every denial code with a guide
Authorization
Bundling
Contractual
Coverage
Data quality
Documentation
Eligibility
Liability and workers comp
Patient responsibility
Provider eligibility
Timely filing
- CO-29Timely Filing Limit Expired
Looking for a different code? Search all 190 CARC and RARC codes
Questions about CO-29
Only with proof of timely original submission. A clearinghouse acceptance report showing the original date is the strongest evidence. Without documentary proof the claim reached the payer inside the window, the revenue is lost.
Commonly ninety days to a year from the date of service, varying by payer, plan and claim type. Secondary claims often run from the primary payer's remittance date rather than the service date. Applying one internal deadline across all payers reliably misses the shorter ones.
No. The CO prefix makes it a contractual obligation, and the failure was administrative rather than the patient's. Billing it to the patient generally breaches the payer agreement.
Work accounts receivable by filing deadline proximity rather than by balance, and load each payer's actual deadline rather than a single internal default. This denial is entirely preventable and entirely permanent, which is an unusual and costly combination.
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