Medicare Timely Filing Deadline: The One-Calendar-Year Rule

Medicare's timely filing rule is more generous than most commercial payers — and more absolute. The statute gives you until the last day of the calendar year following the year in which the service was furnished. That's commonly summarized as "one calendar year," but the calendar-year framing matters: the deadline is always a December 31.

How to calculate your deadline

The formula: take the year the service was furnished, add one year, and the deadline is December 31 of that year.

Service on February 3, 2026 → file by December 31, 2027 (nearly two years).
Service on December 28, 2026 → file by December 31, 2027 (just over a year).
Service on January 2, 2026 → file by December 31, 2027.

Early-year services get the longest effective window; late-December services get the shortest. Either way, the receipt date — when the Medicare contractor receives the claim — is what counts. Compare this with commercial deadlines in our payer-by-payer guide (Aetna 120 days, UHC 90, Cigna and Anthem 180, Humana 180).

Dec 31

Medicare's timely filing deadline is always December 31 of the calendar year after the service year. One rule, no payer-by-payer variation.

The narrow exceptions

Medicare allows exceptions to timely filing only in limited circumstances, and every one requires documentation:

Administrative error — a government agency's error prevented timely filing (for example, the contractor misdirected the claim or gave wrong filing instructions). Your error doesn't count; theirs might.
Retroactive entitlement — the beneficiary's Medicare entitlement was granted retroactively, so timely filing was impossible. The claim must then be filed within a limited window after the entitlement notice.
Other documented circumstances where timely filing was prevented by events outside the provider's control — evaluated case by case, and rarely granted.

Note what isn't an exception: being busy, staff turnover, clearinghouse problems on your side, or not knowing the rule. None of those move Medicare.

What happens to late Medicare claims

A claim filed after the deadline is denied, and the denial carries provider liability — you generally cannot bill the beneficiary for services denied solely because the claim missed timely filing. The revenue is simply gone. This is also why crossover claims and coordination of benefits delays are dangerous with Medicare: if you're waiting on another payer, diary the Medicare deadline anyway.

Illustration of a calendar showing Medicare's one-calendar-year filing deadline

Medicare's rule is simple to state and easy to miss: file by December 31 of the year after service.

Prevention checklist

Run an unfiled-claims report monthly and sort by oldest date of service — anything approaching the year mark gets filed that week.
Don't let COB sequencing eat the deadline. If a secondary payer is slow, file Medicare on time and sort out coordination after.
Monitor rejections daily. A rejected claim isn't filed, and Medicare's clock doesn't pause for your clearinghouse queue.
Diary credentialing-held claims against the December 31 deadline — held claims are the classic way Medicare timely-filing denials happen.

Frequently asked questions

What is Medicare's timely filing deadline?

Medicare claims must be received no later than the last day of the calendar year following the year the service was furnished — effectively one full calendar year. For a service in 2026, the deadline is December 31, 2027.

How is the Medicare timely filing deadline calculated?

Take the year the service was furnished, add one year, and the deadline is December 31 of that year. The contractor's receipt date is what counts, not your submission date.

Can Medicare extend the timely filing deadline?

Only in narrow circumstances: government administrative error that prevented timely filing, retroactive Medicare entitlement, or other documented events outside the provider's control. All require documentation and are evaluated case by case.

What happens if a Medicare claim is filed late?

The claim is denied and the provider is generally liable — you cannot bill the beneficiary for services denied solely because timely filing was missed. The revenue is unrecoverable.

Does waiting on another payer extend Medicare's deadline?

No. Coordination-of-benefits delays do not extend Medicare's timely filing deadline. If another payer is slow, file Medicare on time and resolve coordination afterward.