Timely Filing Limits 2026: Deadlines by Payer

The Denial You Can't Appeal and Can't Bill the Patient For

By Yagnesh Dave  ·  October 1, 2026  ·  11 min read

A ten-provider practice collects $2.4 million a year. Write off 1.5% of that to timely filing denials and $36,000 is gone, with no appeal path and no patient to bill. Nobody made a coding mistake. A charge sat in a queue, a rejection went unread, or a secondary claim waited for a payment that already posted.

Timely filing limits are the least forgiving rule in billing. Every other denial can be argued with documentation, a corrected claim or a clinical letter. A claim that arrives after the deadline is usually dead, and the contract rules in most cases that you can't bill the patient for it either.

Here's what the 2026 deadlines look like by payer type, where the clock really starts, what counts as proof, and the worklists that keep claims from aging out.

Timely Filing Limits by Payer Type

The limit depends on who you bill, and you won't find a single number that covers your whole payer mix. Use this table as a starting point, then confirm against each contract.

Two things in that table matter more than the numbers. The commercial range is wide, so a contract renewal can quietly cut your window from 180 days to 90. And Medicare Advantage plans don't follow the 12-month Medicare rule for contracted providers, which catches practices that assume they do.

Texas Medicaid has used a 95-day window for years, while Florida Medicaid allows up to 12 months. Same program, very different deadlines.

The Medicare Timely Filing Limit and Its Exceptions

For Original Medicare, a claim has to reach the Medicare Administrative Contractor (MAC) within 12 months of the date of service. The Affordable Care Act shortened what used to be a longer, calendar-year-based window, and the rule now sits in 42 CFR 424.44 and Chapter 1 of the Medicare Claims Processing Manual.

The exceptions are narrow. The main ones are administrative error by CMS or one of its contractors, such as bad advice or a lost claim, and retroactive Medicare entitlement, where a patient's coverage is backdated after you provided the service. Forgetting to bill isn't an exception. Neither is a clearinghouse outage unless you can show the claim was submitted on time and the failure wasn't yours.

When a late claim does get through, the denial shows up with group code CO and CARC 29, "The time limit for filing has expired." CO means contractual obligation, which tells you the loss is yours to absorb.

Rejected vs. Denied: Where the Filing Clock Really Stops

This is where practices lose the most money. A rejected claim never made it into adjudication. It failed an edit at the clearinghouse or the payer's front end, usually for missing data, a bad ID or a format error. A denied claim was processed and refused.

Many payers treat a rejected claim as never filed. That means a claim rejected on day 5 and quietly ignored until day 100 has used up most of a 90-day commercial window, and the resubmission arrives late.

The fix is operational. Open every clearinghouse rejection report each business day, assign each rejection to a person, and set a rule that nothing sits more than 48 hours. A practice that submits 600 claims a month with a 4% front-end rejection rate has 24 rejections a month to fix. At an average of $140 a claim, that's $3,360 a month at risk if they aren't worked.

Proving Timely Filing When a Payer Denies for Late Submission

Payers accept a short list of evidence. You'll want it organized before you ever need it.

Proof payers usually accept

• A clearinghouse acceptance report or payer acknowledgment (999 or 277CA) dated before the deadline
• A payer portal screenshot or confirmation number showing the original submission
• A prior remittance advice that shows the payer processed the claim, including a denial for another reason
• Certified mail receipts for paper claims

Proof payers usually refuse

• A billing system screen that shows "billed" without a payer receipt
• An unsigned internal note
• A claim with different charges, dates or patient identifiers than the one the payer received

An appeal with a clean acceptance report has a real chance of overturning a timely filing denial, and one without it almost never succeeds. If you bill through a vendor, require them in the contract to keep acceptance reports for at least three years and produce them on request within five business days.

Secondary and Corrected Claims Have Their Own Clocks

Secondary billing is where deadlines hide. Many secondary payers measure from the date of service, not from the date the primary paid. Others measure from the primary's remittance date, usually with a window of 60 to 180 days. If you wait for a primary payer who takes 45 days to adjudicate and then send the secondary on day 100, a 90-day secondary limit is already gone.

Corrected claims and resubmissions often run on a shorter timer than the original. Some payers give 180 days from the original remit date, others only 90, and a few start the count from the date of service again. Put the corrected claim rule for each payer in your matrix, not just the original limit.

And remember Medicare as the secondary payer. When Medicare is secondary, the 12-month rule still applies, which is another reason not to leave a primary payer's slow response unmonitored for months.

Timely Filing Audit and Compliance Exposure

Timely filing isn't a coding audit item, but it ties directly to money and to compliance. CMS's fiscal year 2025 data puts the Part B provider improper payment rate at 8.44%, or $9.62 billion, and a big part of that traces to documentation. When you rebill a claim after a denial, the original documentation has to support it.

The audit risk in timely filing is what you do after a miss. Medicare contractors can reopen claims within 1 year for any reason and within 4 years for good cause, and a changed claim that suggests a date was altered draws attention fast. Recovery auditors generally review a three-year lookback, so a pattern of late claims with cleaned-up dates can surface long after the fact.

Compliance teams should keep a simple log: claim, original submit date, rejection date, fix date, resubmit date, outcome. When the log shows a claim reached the payer on time, you can prove it. When it shows a miss, you can show the write-off was handled correctly.

Frequently Asked Questions About Timely Filing Limits

What is the Medicare timely filing limit?

Medicare Part B claims must be received by your Medicare Administrative Contractor within 12 months of the date of service. There are narrow exceptions, such as administrative error by CMS or a contractor and retroactive Medicare entitlement.

Can I bill the patient if a claim denies for timely filing?

Usually not. A Medicare timely filing denial is a provider liability under the limitation on liability rules, and most commercial contracts also bar balance billing the patient for a denial caused by late filing.

Does a rejected claim count as filed on time?

Often not. A claim rejected at the clearinghouse or payer front end never entered adjudication, so many payers treat it as not filed. Work rejections the day you receive them and keep the original acceptance report.

What proof do payers accept for timely filing appeals?

A clearinghouse acceptance report or payer acknowledgment (such as a 277CA) showing the payer received the claim before the deadline, with the patient, date of service and charges matching the original claim.