The most common reason a legitimate claim becomes permanently uncollectable has nothing to do with medical necessity, coding accuracy, or documentation quality.

It ran out of time.

Timely filing limits are the payer’s contractual right to deny a claim solely because it was submitted outside the allowed window — regardless of whether the service was covered, the coding was correct, or the patient was eligible. The denial is final. There is no clinical appeal. The money is gone.

Here is the full tactical breakdown: what the limits actually are, where the exposure hides, and how to build a workflow that stops the bleed before it starts.

The Limits Vary More Than You Think

Timely filing limits are set by contract, not by law. Every payer sets its own. The variation is significant:

• Medicare: 12 months from date of service (with limited exceptions)
• Most commercial payers: 90 to 180 days from date of service
• Some commercial payers: As short as 30–60 days
• Medicaid: Varies by state — ranges from 90 days to 24 months
• Medicare Advantage: Set by the plan, not CMS — often 90 to 180 days, sometimes shorter

The critical distinction: the clock starts on the date of service, not the date you submitted the claim, not the date the claim was rejected, not the date you became aware of a problem.

Where the Exposure Hides

Timely filing denials cluster in predictable places. If you have a 90-day-old AR bucket with significant balances, you are looking at active exposure right now.

Clearinghouse Rejections That Nobody Is Watching

A claim submitted through your clearinghouse that is rejected before reaching the payer — wrong format, missing field, eligibility mismatch — never generates a payer denial. It generates a clearinghouse rejection that sits in a worklist. If that worklist is not being worked daily, the claim ages undetected. By the time someone pulls the aging report, the timely filing window has closed.

Coordination of Benefits Delays

When a patient has primary and secondary coverage, the secondary claim cannot be submitted until the primary has adjudicated. If the primary takes 60 days to process and the secondary payer has a 90-day limit from date of service, you have a 30-day window to submit the secondary. Practices that batch secondary submissions weekly — or that wait until the primary EOB arrives in the mail — routinely miss this window.

Eligibility Verification Gaps at Check-In

A claim submitted to the wrong payer — because the patient’s coverage changed and the practice didn’t catch it at the front desk — will deny for eligibility. Resubmitting to the correct payer after the denial often falls outside the timely filing window for that correct payer. The eligibility error at check-in becomes an uncollectable claim 90 days later.

New Provider Credentialing Delays

When a new provider joins a practice and their credentialing is pending, claims are often held or submitted under another provider’s NPI. When credentialing is finalized and the claims are corrected and resubmitted, the resubmission date may fall outside the original timely filing window.

The Workflow Fix

Timely filing exposure is a workflow problem, not a coding problem. The fix is operational.

Daily clearinghouse rejection review. Assign a specific staff member to clear the clearinghouse rejection worklist every morning before noon. Every rejection gets worked the day it appears. Not batched, not weekly — daily. This single change eliminates the single largest source of timely filing exposure.

COB tracking by claim, not by batch. For every claim with known secondary coverage, log the primary submission date and calculate the secondary filing deadline at time of submission. When the primary EOB arrives, the secondary submission deadline is already in the system. Do not wait to calculate it.

30/60/90 AR report with timely filing flags. Your AR aging report should flag every claim approaching a payer-specific timely filing threshold. At 60% of the window, flag for review. At 80% of the window, flag as urgent. Claims that reach 90% of their timely filing window without a clean acceptance on file go to the billing manager — not the worklist.

Timely filing limit reference sheet by payer. Build a one-page reference document listing the timely filing limit for every payer in your network. Post it at every billing workstation. Update it when contracts renew. This is not a sophisticated system. It is the foundation.

What to Do With the AR That’s Already Aged

If you have claims in your 90-day-plus bucket that are approaching or past their timely filing limit, you have three options — and only one of them recovers money.

Option 1: Submit anyway with documentation. Some payers will consider a late claim if you submit proof that the original claim was timely filed and the denial or rejection was due to payer error or system failure. This requires documentation: the original submission confirmation, the clearinghouse acknowledgment, and the payer’s rejection. No documentation, no exception.

Option 2: Patient billing (where appropriate). If the claim is uncollectable from the payer, review whether the balance is billable to the patient under the terms of the payer contract and the patient’s financial responsibility. Not all balances can be shifted — contracted payer agreements often prohibit balance billing beyond patient cost-sharing.

Option 3: Write it off and learn from it. For balances that are genuinely uncollectable — past the filing limit, no documentation of timely filing, not billable to the patient — write it off, code the denial reason accurately in your system, and use the write-off data to identify which part of the workflow failed. The write-off is tuition. Use it.

Your Action Item This Week

For claims already past their timely filing limit: document the original submission date, determine whether a payer exception is available, and if not, initiate write-off review.

That is your timely filing audit. Run it this week.

For the full timely filing management playbook — including payer-specific limit reference, COB tracking template, and 30/60/90 escalation workflow: Timely Filing Playbook →