How to overturn a timely filing denial

Why this denial feels final and often is not

CO-29 says the claim was received after the filing limit. Most practices read it as closed, write the balance off and move on. That is right roughly half the time. The other half, the claim was submitted inside the window and something happened to it in transit — and the payer has no way of knowing that unless somebody shows them.

The one thing that wins these

Proof of timely submission. Not a note saying you sent it, not a screenshot of your billing system, but the clearinghouse record: the 999 acknowledgement showing the file was accepted, or the 277CA showing the claim status, with the date. That document is what converts an argument into a fact, and payers reverse on it routinely.

This is why the clearinghouse reports matter more than any note in the practice management system. Your own system records what you intended to send. The clearinghouse records what actually left, and when.

Work it in this order

1. Find out what the limit actually is

It is a contract term, not a law, and it varies enormously — 90 days on some commercial contracts, a year on others. A denial applying a 90-day limit to a contract that says 180 is simply wrong, and that happens more than people expect. Read the contract before writing anything.

2. Establish the date the payer says it received the claim

Get it from them, in writing, with a call reference number. Half of these disputes turn out to be about a date rather than about the rule.

3. Pull the clearinghouse acknowledgement

The 999 for the file and the 277CA for the claim. If the claim was accepted inside the window, you have your evidence. If it was rejected at the clearinghouse and never reached the payer, that is a different and more painful finding — the claim was never filed at all, and the rejection sat in a queue nobody worked.

4. Check for a valid exception

Retroactive eligibility, coordination of benefits where another payer was primary and adjudicated late, and a corrected claim on a claim originally filed on time are the common ones. Each has its own rules and each has to be stated explicitly in the appeal.

5. Appeal in writing, with the evidence attached

One page. What was submitted, when, the acknowledgement proving it, the contract term, and the request. Do not argue fairness — a timely filing appeal that contains an opinion rather than a date is one that gets denied again.

The rejection nobody sees

The most expensive version of this is not a denial at all. A claim rejected at the clearinghouse never reached the payer, so it is not denied, not appealable, and still inside its filing window — until it is not. It sits in a rejection queue looking like nothing, and it ages exactly like a claim that was submitted.

A practice with an unworked rejection queue is generating future timely filing write-offs at a steady rate and cannot see it on any aging report. Working that queue to zero every week is worth more than any appeal process.

What prevents it

Two habits. Reconcile every submission batch against its acknowledgement, so a file that failed is known the same day. And work the rejection queue on a schedule rather than when somebody notices. Both are unglamorous, and between them they remove almost the whole category.