Every Medicare Visit From Late 2025 Has a Deadline This Month or Next. After It, the Patient Can't Be Billed Either.

Under 42 CFR 424.44, a Medicare fee-for-service claim must be filed no later than the close of the period ending one calendar year after the date of service. A visit on November 10, 2025 must reach the Medicare contractor by November 10, 2026. A visit on December 22, 2025 must arrive by December 22, 2026.

Most claims go out within days, so the limit rarely matters. It matters for the claims that got stuck: a claim held for a missing signature or a referring provider, a claim that kept coming back as unprocessable, a patient whose Medicare number was wrong, or a visit that was never entered at all. Those claims tend to sit in a held or rejected queue until someone notices. At year end, some of them are about to run out of time.

Why a late claim costs more than the payment

The Medicare Claims Processing Manual, chapter 1, section 70.4, says a claim is denied if its receipt date is more than 12 months after the date of service. That denial is not an initial determination, so it is not subject to appeal. There is no redetermination and no second look.

The same section also protects the patient. When the provider is responsible for not filing on time, the provider may not charge the beneficiary for the services, except for the deductible and coinsurance that would have applied if Medicare had paid. The money is simply lost.

Section 70.5 closes one more door. If a service was left off the original claim, an adjustment to add it is not allowed once the filing limit for the original claim has passed.

What counts as filed

The clock stops on the date the Medicare contractor receives a valid claim, not on the date your system sends it. A submission that is returned for missing or invalid data is not a filed claim. It has to be corrected and sent again, and the corrected claim must still arrive inside the 12 months.

For professional claims (the CMS-1500 or 837P), the start date is the line item From date. If a line spans dates, such as a supply or rental, and only the later dates are still timely, the contractor splits the line and denies the untimely part. A service on February 29 must be filed by February 28 of the next year. If the last day falls on a weekend or federal holiday, the deadline moves to the next workday.

The exceptions are narrow

42 CFR 424.44(b) allows only a few extensions. Each one runs through the last day of the sixth calendar month after the month in which the problem is fixed or the notice is received:

• Administrative error: an error or misrepresentation by Medicare or its contractor caused the late filing. Requests more than four years after the date of service are not eligible.
• Retroactive Medicare entitlement: the patient was not entitled to Medicare on the date of service and was later made entitled back to that date.
• Retroactive entitlement where a state Medicaid agency took back its payment six or more months after the service.
• Retroactive disenrollment from a Medicare Advantage plan or PACE organization, where the plan took back its payment six or more months after the service.

A staff member who was out, a billing system change or a vendor backlog is not on this list.

A one-hour check to run this week

This is general information, not legal advice. Before the end of November, pull these reports and work them oldest first:

• Every Medicare claim with a date of service before January 1, 2026 that is unbilled, on hold or rejected and not yet accepted. Sort by date of service and note the deadline for each.
• Every Medicare visit from November and December 2025 with no claim at all. Compare the schedule to charges for those two months.
• Medicare claims in a rejected or unprocessable status. Check the acceptance report from the clearinghouse, not only the practice system.
• Any patient whose Medicare Advantage plan took back a payment for a 2025 visit. Write down the date of the recoupment, because the six-month extension counts from that month.
• Every commercial and Medicare Advantage contract. These plans set their own filing limits in the contract, and you should not assume they allow 12 months.

Small queues, real money

A held claim does not look like a denial until the day it becomes one. Clearing the oldest items each week keeps the year-end deadline from becoming a write-off. If you want to know how much of this is happening in your practice, a revenue review can look at one payer's denials over the last 90 days and show which ones started as a late or rejected claim.