Timely filing limit

Every payer sets its own window. Commercial plans put it in the provider contract or the administrative guide, Medicaid programs set it in state rules, and Medicare publishes its rule on medicare.gov: claims must be filed no later than 12 months, one full calendar year, after the date of service¹. The clock usually starts on the date of service, or on the discharge date for an inpatient stay, and a payer can run a separate clock for secondary claims that starts when the primary payer’s remittance was issued. Read the contract for each payer rather than assuming the Medicare rule applies.

A timely filing denial is a dead loss. It is not a coding problem you can correct and resend; once the window closes the payer will not review the claim on its merits, and network contracts generally keep you from billing the patient for it. Unbilled charges, rejected claims that nobody re-sent, and claims stuck at the clearinghouse all burn the window silently, because nothing in the system looks like a denial until the payer finally sees the claim.

The mistake is assuming submitted means received. A clearinghouse rejection means the payer never got the claim, and your own submission log proves nothing to the payer. Proof of timely filing is the payer’s acceptance report, the 277CA, or a claim number from the payer’s system. Run a report of claims with no payer acknowledgment every week, and treat the shortest window across your payer mix as the house deadline.