Timely Filing Deadlines: What Happens When a Claim Is Late

When a claim misses a timely filing deadline, the payer denies it as untimely, and in most cases the practice cannot bill the patient for it. Under Original Medicare, a late-filing denial is not an "initial determination", so it cannot be appealed; the only route is one of four narrow exceptions. Commercial payers usually let you dispute the denial only with proof that the claim was received on time.

• Medicare deadline: 12 months from the date of service.
• Medicare late claims: no appeal rights; an extension is possible only for Medicare administrative error, retroactive entitlement, retroactive entitlement involving a state Medicaid agency, or retroactive Medicare Advantage or PACE disenrollment.
• Patient billing: Cigna and UnitedHealthcare both say you cannot bill the patient for a claim denied as late. Medicare allows only the deductible and coinsurance that would have applied.
• Commercial disputes: UnitedHealthcare reviews a timely filing denial through its reconsideration process if you send proof the claim was received and accepted within your limit.
• Corrected claims: Medicare treats corrections to a timely claim as reopenings, but you cannot add a new service after the filing limit has passed. UnitedHealthcare applies your contract's filing limit to corrected claims too.

Check your contract; limits vary by plan and contract.

Sources checked October 14, 2026 · Prepared by Prospyr. This update replaces an earlier version that included statistics and payer day counts we could not verify. No certified-coder or billing-specialist review is claimed.

For payer-by-payer limits, see Timely Filing Limits by Payer. This page covers what happens when a deadline is missed and how to prevent it.

Medicare: why a late claim cannot be appealed

The Medicare Claims Processing Manual, chapter 1, section 70.4, says that when a claim is denied for being filed after the timely filing period, the denial "does not constitute an 'initial determination'" and "is not subject to appeal." Sending a redetermination request will not help.

What you can do is ask your Medicare Administrative Contractor for an exception under 42 CFR 424.44(b), with documents that show which exception applies:

1. Administrative error: a Medicare employee, contractor or agent caused the delay.
2. Retroactive Medicare entitlement: the patient was granted Medicare coverage back to or before the date of service.
3. Retroactive entitlement involving state Medicaid agencies: Medicaid paid first, then recouped its payment six months or more after the service once Medicare entitlement was made retroactive.
4. Retroactive disenrollment from Medicare Advantage or PACE: the plan recouped its payment six months or more after the service.

Your contractor's website explains how it wants these requests sent. Ordinary reasons, such as team turnover or a software problem, are not on the list.

If the provider caused the late filing, Medicare says the provider may not charge the patient except the deductible and coinsurance that would have applied had Medicare paid.

Corrected claims and adjustments under Medicare

The same manual (section 70.5) separates two things:

• Adding a missed service: if a service was left off the original claim, you cannot add it in an adjustment after the filing limit for the original claim has passed.
• Correcting a timely claim: a bill that corrects information on a claim that was filed on time is handled as a reopening, under the reopening and administrative finality rules (chapter 34), not the filing limit.

Commercial payers: proof of timely filing

Commercial payers set their own rules, but the common thread is proof. UnitedHealthcare's 2026 guide says proof of timely filing must show:

• The date the claim was submitted to UnitedHealthcare or another payer.
• The date it was accepted.
• Member identification information.
• The date of service.
• Provider identification.

Acceptable documents include an EDI report, a billing or accounting software statement, or an EOB, another carrier's denial or a dated eligibility rejection letter with a resubmission form. A rejected claim does not count, because a rejection needs action before the claim can be processed.

Cigna's rules add that a resubmission Cigna did not ask for, and that is not an appeal, is held to the filing limit. Cigna may ask for evidence of extraordinary circumstances, such as a natural disaster, that prevented timely filing.

How to prevent late-filing denials

• Confirm the payer before the visit. Check eligibility and the plan type (commercial, Medicare Advantage, Medicaid managed care). Sending a claim to the wrong payer uses up filing time.
• Sign charts promptly. A claim cannot be built from an unsigned note.
• Submit on a regular schedule. Set an internal target well inside your shortest contracted limit.
• Work rejections daily. Clearinghouse and payer rejections do not stop the clock.
• File your proof. Keep acknowledgment reports and acceptance confirmations with each claim so you can produce them later.
• Track secondary claims separately. Many payers count the secondary claim's limit from the primary payer's EOB date, so log that date when the EOB arrives.

Where Prospyr fits

Prospyr supports charting, digital intake, inventory and practice operations; practices that bill insurance heavily need a separate claims solution.

Sources

• CMS, Medicare Claims Processing Manual ch. 1 §§70.4–70.7, Transmittal 12909 (2024)
• UnitedHealthcare 2026 Care Provider Administrative Guide
• Cigna, When to file claims