You saw the patient. The note is signed, the codes are right, and the claim went out the door. Then the remittance lands with one line: "Time limit for filing has expired." There is no appeal to file and no phone call that fixes it. The money is gone.
Medicare timely filing denials are climbing on practice denial reports, and the painful part is that nothing was wrong with the care or the coding. The claim just showed up late. That is a completely avoidable loss, and most practices only learn how it happened after the damage is done.
We have 150+ years of combined experience at A2Z Billings, and we have watched this one denial drain real money from good practices. This guide gives you the exact rule, how Medicare counts the days, the four narrow exceptions, and the habits that keep every claim inside the window.
What the 12-Month Rule Actually Says
Medicare gives you one calendar year from the date of service to file a fee-for-service claim. That covers Part A and Part B. Miss it and the claim is denied.
It used to be looser. Before the Affordable Care Act, providers had anywhere from 15 to 27 months, depending on when the service happened. Section 6404 of the ACA cut that to a flat 12 months. Some billing teams still work with the old cushion in their heads, and that habit is expensive.
The rule sits in Chapter 1, Section 70 of the Medicare Claims Processing Manual and in federal regulation 42 CFR 424.44. The number is easy to remember. The counting is where people trip.
How Medicare Counts Your Days
A year sounds simple until you look at how the date gets picked.
- Line-item dates: If a service reports a line-item date, that date starts the clock. Otherwise, the From date on the claim does.
- Span claims: Part B uses the From date. Part A institutional claims use the Through date.
- Leap day: A service on February 29 has to be filed by February 28 of the following year.
- Paper claims: Medicare goes by the day the contractor receives the claim, not the postmark.
- Electronic claims: First Coast Service Options, for one, treats EDI claims received after 6 p.m. ET, or on a weekend or holiday, as received the next business day.
That last point matters. "We sent it Friday night" can turn into "Medicare got it Monday." If you are filing on the final day, you are already gambling.
Why These Denials Keep Piling Up
Nobody plans to miss the deadline. Claims slip through gaps in the workflow, and the same gaps show up again and again.
Rejections that nobody works.
A claim bounces at the clearinghouse or at a front-end edit and sits in a report nobody opens. A rejected claim is not a filed claim, so the clock keeps running while it waits.
Returned claims.
Medicare sends back claims with missing or invalid data as unprocessable. Fix and resend them right away, because the deadline does not pause for your first attempt.
Slow charge entry.
Notes wait on signatures, coding questions, or missing records. The claim gets built in month five, and any error eats the runway that is left.
Secondary claims.
When Medicare is the secondary payer, the same 12 months from the date of service apply. A slow primary payer does not stop the clock.
Turnover and backlogs.
When a biller leaves, a pile of half-worked claims often stays behind with no owner.
Late eligibility changes.
Coverage updates arrive after the claim went to the wrong payer, and the fix starts too late.
How a Clean Claim Still Ends Up Late
Here is a pattern we see all the time. A patient is seen in the first month of the year. The charge is coded correctly, but the claim is rejected at the clearinghouse over a missing identifier. The report sits unopened because the biller who owned it is out sick. Nobody notices for weeks, then months. By the time someone spots it, the claim is eleven months old, and the fix needs a corrected record, a resubmission, and a few days of back-and-forth.
One missed step at the front end, one person off for a week, and a perfectly good claim is now racing a deadline it could have beaten by a mile. Nobody was careless. The system simply had no alarm.
What One Missed Deadline Really Costs
Say your practice sends 500 Medicare claims a month at an average payment of $110. If 2% miss the deadline, that is 10 claims, $1,100 a month, and $13,200 a year. Your team already did the work, and you will not get a dollar of it back.
Most denials can be corrected and resent. A coding mismatch can be fixed. A missing document can be attached. A late-filing denial is different because the door is shut. There is nothing to correct and nothing to argue, so your denial team has nothing to chase.
It also lands on your side of the table. Because the delay was not the patient's doing, the balance generally stays with the practice.
You Cannot Appeal It, But You Might Have a Way Out
A claim denied for late filing is not an initial determination. That means it carries no redetermination rights, and an appeal request gets dismissed. Skip the appeal and save yourself the weeks.
What you can do is ask for an exception through a reopening, but only if one of four situations applies. Each one extends the limit through the last day of the sixth month after the triggering event.
- Administrative error. An employee, contractor, or agent of HHS performing Medicare functions made an error or gave wrong information that caused the delay.
- Retroactive Medicare entitlement. The patient was not entitled to Medicare on the service date, then received notice of entitlement going back to or before that date.
- Retroactive entitlement involving a state Medicaid agency. The agency recouped its payment six or more months after the service for a dual-eligible patient.
- Retroactive disenrollment from a Medicare Advantage or PACE plan. The plan recouped payment six or more months after the service because the patient was disenrolled back to or before the date of service.
Being busy, short-staffed, or let down by a clearinghouse is not on the list. You also need paper proof, such as an agency letter, a Medicaid recoupment notice, or a disenrollment letter. CGS notes that a written exception request can take up to 45 business days to get a response, so send it the moment you spot the problem.
A Simple Timeline That Protects Every Claim
Deadlines stop hurting when every claim has milestones. Here is a schedule any practice can copy.
- Days 1 to 3: Charges entered and coded.
- Days 4 to 7: Claim scrubbed and submitted.
- Day 14: Acceptance confirmed. Anything rejected gets fixed and resent.
- Day 45: Unpaid claims get a status check.
- Day 90: Your red line. No claim should still be unbilled or unresolved.
- Day 270: Final alarm. Every open claim gets a named owner and a same-week deadline.
The real limit is a full year, but this schedule leaves you three months of breathing room. That cushion is the difference between a problem you can fix and a loss you have to write off.
Habits That Keep Claims Inside the Window
Bill fast. Submit within days of the visit, not weeks.
Work rejections the day they arrive. Give one person ownership of every clearinghouse and payer rejection report, and have them check it daily.
Keep proof. Save clearinghouse acceptance reports and payer acknowledgements for every claim. If a denial is wrong, this is the file that overturns it.
Age your claims weekly. Run a report by days since the date of service, and look hardest at anything unbilled.
Check eligibility before the visit. Fewer payer surprises means fewer claims stuck in the wrong queue.
Cover absences. Every billing task needs a backup person, so a vacation or a resignation never freezes a queue.
What to Do When the Denial Hits
Pull the claim and compare the date of service with the date Medicare received it. Sometimes the denial itself is wrong, and your acceptance report proves it. If that is the case, send a reopening request with the proof attached.
If the dates hold up, check your situation against the four exceptions above. If one fits, gather the letter and file the request right away.
If nothing fits, write it off according to your policy, then find the gap that let it happen. The fix is almost always a rejection queue nobody owns, an aging report nobody runs, or a missing backup.
Stop Losing Money You Already Earned
Every Medicare claim that dies on the vine is revenue your providers earned and you never collected. A2Z Billings exists to stop that. Our team brings 150+ years of combined experience to your billing, and the result for you is simple: claims go out fast, rejections get worked the same day, and your aging report gets watched every week so nothing drifts toward the cliff. You keep what your providers earned, and you stop chasing deadlines.
Here is an easy first step. Send us your current aging report. We will flag every Medicare claim sitting closer to the 12-month limit than it should be, so you can see what is at risk before it turns into a denial. Reach out today and get your deadlines under control.
Frequently Asked Questions
How long is Medicare's "timely filing" period?
All fee-for-service claims, Medicare Advantage plans, and commercial payers have limits based on a calendar year.
Do I have the ability to appeal a Medicare timely filing denial?
No. A denial filed in a timely way is not an initial determination, and requests for redetermination are rejected. One may only request a reopening if one of the four exceptions applies, or if the denial was incorrect and on-time receipt can be proved.
What does CARC 29 mean?
It means "The deadline for submitting the application has passed. Medicare will report it on the remittance and let you know that the claim was submitted late.
May I charge the patient for a claim denied because it was filed late?
Generally no. This delay was on the provider side, and the balance remains at the practice. Before submitting any statement, please review Medicare rules and your payer agreements for your specific scenario.
When does the clock tick – the date of the service or the date I bill?
It begins on the day of service. If the claim has line item dates, then the line date is counted. Otherwise the From date on the claim is used unless on a Part A span claim, then the Through date is used.
Does Medicare Advantage have the same deadline?
Not necessarily. Depending on the provider contract, each plan has a different filing limit which may be less than or more than 12 months. Take out the contract for each plan you bill and have the limits on one sheet.
Do secondaries receive additional time?
No. If Medicare is second to pay, the limit applies from the date of service. Do not confuse the "waiting on a primary payer" period; it does not count toward it and will be counted from the first day.
How many days does it take to process a filing exception request?
This depends on the contractor. A written request may take up to 45 business days for research and for a response to be provided, says CGS. Submit the request together with all supporting letters as a single package, as it generally takes longer to receive a request if one of the supporting letters is missing.
What is the evidence that a statement is sent on time?
Reports and Payer Acknowledgment for the Clearinghouse prior to the deadline. Keep them to make any claims. In the case of paper claims, the date the contractor receives the claim will be considered the date of the claim, and a mailing receipt is not strong proof.