How to Appeal a Timely Filing Denial

Timely filing denials are frustrating because they have nothing to do with whether the service was covered or the claim was coded correctly. The payer is simply saying: you didn't submit this within the filing deadline we require. But timely filing denials are also among the most recoverable — if you know what documentation you need and how to present it.

Know the Timely Filing Window First

Every payer sets their own timely filing deadline, and they are not all the same. Common windows:

• Medicare: 12 months from date of service
• Medicaid: Varies by state — anywhere from 90 days to 24 months
• Commercial payers: Typically 90–180 days, but some are as short as 60 days or as long as 12 months

Before you appeal, confirm what the filing deadline actually is for this payer and plan. If you filed within the deadline and received a CARC 29 anyway, that is a payer processing error and the strongest possible basis for appeal.

Documentation That Wins Timely Filing Appeals

The single most important piece of evidence is proof of timely submission. Gather as many of these as apply:

• Electronic Acknowledgment (999 or 277CA). If you submitted electronically, your clearinghouse generates a 999 functional acknowledgment and a 277CA claim acknowledgment. These contain timestamps that prove when the claim was submitted and that it was accepted. This is your strongest evidence.
• Clearinghouse submission log. Most clearinghouses maintain a submission history with date stamps. Download and include this.
• Payer portal submission confirmation. If submitted via portal, take a screenshot of the confirmation with date and claim number visible.
• Certified mail receipt. For paper claims, a certified mail receipt with postmark date is your timestamp.
• Prior authorization or referral date. If prior auth was obtained before the filing deadline, that also establishes a timeline.

Exceptions That Override the Deadline

Even if you genuinely filed late, there are circumstances that can override the timely filing deadline. Document and cite any of the following that apply:

• Retroactive eligibility. If the patient's coverage was applied retroactively, the filing window starts from the date eligibility was confirmed — not the date of service.
• Coordination of Benefits delay. If you were waiting for primary insurance to adjudicate before billing the secondary, and that delay caused the secondary filing to be late, document the primary EOB date.
• Payer billing suspension or natural disaster. CMS and most commercial payers waive timely filing requirements during declared emergencies. Reference the specific waiver if applicable.
• Administrative error. If the denial resulted from a payer-side error (wrong address on file, claim rejected and returned with no notification), document the circumstances.

Writing the Appeal Letter

A timely filing appeal letter should be direct and evidence-forward. Lead with your proof of timely submission — don't bury it in the third paragraph. Structure:

1. State the claim number, date of service, patient, and the denial reason (CARC 29)
2. State that the claim was submitted within the required filing period and provide the specific date
3. Attach the electronic acknowledgment or clearinghouse log as Exhibit A
4. If citing an exception, state the exception clearly and attach supporting documentation
5. Request reconsideration and reprocessing of the claim

If the Appeal Is Denied

If the first-level appeal fails, escalate to second-level review. If your clearinghouse logs clearly show timely submission, you have a strong case and it is worth pushing. Some payers have a formal dispute resolution process separate from clinical appeals — timely filing disputes often route there rather than to clinical review.

If you exhausted the appeals process and the denial stands, the patient is not responsible for timely filing denials — this is a provider-side billing failure. The claim should be written off.

Prevention: Stop Timely Filing Denials Before They Happen

• Build a claims aging report that flags any unacknowledged claims at 30 days — well before any payer's deadline
• Set calendar alerts for any claim that has been sitting in a secondary billing queue beyond 60 days
• Know every payer's filing deadline and document it in your payer contract reference
• Review clearinghouse rejection reports daily — a rejected claim that sits unworked for weeks is a timely filing denial waiting to happen