Timely Filing Limits: Deadlines, Exceptions, and How to Never Miss One

July 9, 2026  |  8 min read  |  LegitMedBilling Team

Timely filing is billing's least forgiving rule: miss the deadline and the claim is worth nothing — and you can't bill the patient for it either. Every payer sets its own window, the windows range from 90 days to a year, and the clock has more edge cases than most billers realize. This guide covers the limits, the exceptions that still get late claims paid, and the workflow that makes deadlines irrelevant.

Typical Filing Limits by Payer Type

Medicare: 12 months from the date of service — the most generous major payer. Medicaid: state-dependent, commonly 90 to 365 days, with managed-care plans sometimes setting shorter windows than the state program. Commercial payers: typically 90–180 days, though your specific contract may say anything from 60 days to 15 months — the contract controls, not the payer's usual habit. Secondary claims: usually measured from the primary payer's EOB date rather than the date of service. Corrected claims and appeals: separate deadlines entirely, often 90–180 days from the remittance. Treat every number here as a default to verify, not a promise — and keep a one-page grid of YOUR contracts' limits where the billing team can see it.

Timely Filing Limits by Payer (2026 Reference)

The ranges below are the windows most commonly seen in provider manuals. They are a starting point, not a substitute for your contract — filing limits are negotiated per agreement, differ by state and by product line within the same insurer, and a participating contract frequently carries a shorter window than the non-par default. Always confirm against your executed agreement or the payer's current provider manual before relying on a date.

Payer-specific detail, including how the commercial and Medicare Advantage windows differ: Cigna, Humana, Aetna, UnitedHealthcare, BCBS and Medicare.

Medicaid works differently from every other payer here — see our Medicaid billing guide for why each state is effectively a separate payer, how managed care changes the rules, and why balance billing a Medicaid patient is generally prohibited.

Once you know your payer's window, our timely filing calculator converts it into the actual deadline date and tells you how many days are left. If a claim already denied for late filing, CO-29 is the code you will see on the remit.

When the Clock Starts (and What Counts as Filed)

The clock starts at the date of service for primary professional claims (discharge date for inpatient stays), and it stops only when the payer receives the claim. That word does heavy lifting: a claim rejected at the clearinghouse was never received — no appeal rights, no record, clock still running. This is why unworked rejection reports are the leading cause of timely filing write-offs, and why acceptance reports are the single most valuable document in a filing dispute.

The Exceptions That Still Get Late Claims Paid

Proof of Timely Submission

If your clearinghouse acceptance report shows the payer accepted the claim inside the window, a CO-29 denial is very winnable — attach the report, cite the acceptance date, request reversal. This is the strongest and most common exception.

Payer-Caused Delays

Retroactive eligibility (common with Medicaid and newborns), COB updates the patient completed late, and payer enrollment errors all support filing exceptions at most plans — document the cause and the timeline.

Good-Faith Filing With the Wrong Payer

Billed the coverage you were given, got the denial months later, and the real payer's window closed meanwhile? Most payers grant exceptions when you attach the original payer's denial as proof of good-faith timely filing. Our CO-29 guide includes the appeal wording for each scenario.

The Workflow That Makes Deadlines Boring

Practices that never think about timely filing all run the same routine: charges out within 48–72 hours of the visit, clearinghouse rejections worked every morning, unbilled-encounter reports weekly, and payer-specific deadline alerts on anything aging. Use our free timely filing deadline calculator to check any claim's runway — and if the math says you're already late, read the CO-29 guide before writing anything off. A meaningful share of 'expired' claims still gets paid by billers who know which exception fits.

One final rule that surprises practice owners: timely filing write-offs can never be billed to the patient. The deadline was the provider's responsibility, and both payer contracts and CMS rules keep it that way — which makes prevention worth more than any recovery effort.