Patent Expiration Date FAQ
Everything you need to know about patent expiration dates — how they work, what affects them, and how to find them.
Patent Term Basics
How long does a patent last?
US utility patents last 20 years from the earliest priority filing date (post June 8, 1995). Design patents filed after May 13, 2015 last 15 years from the issue date. Plant patents last 20 years from filing. The actual expiration can differ significantly due to PTA, PTE, terminal disclaimers, and maintenance fee lapses.
What is a patent expiration date?
The date when a patent's enforceable rights end. After this date, the invention enters the public domain and anyone can freely practice it. The expiration is calculated from the filing date plus the statutory term, adjusted for PTA, PTE, and terminal disclaimers.
What happens when a patent expires?
The invention enters the public domain. Anyone can make, use, sell, or import the patented invention without a license or royalties. However, other patents in the same family may still be active — always check related patents before assuming freedom to operate.
What's the difference between a filing date and issue date?
The filing date is when the application was submitted to the USPTO. The issue date is when the patent was officially granted — the gap can be 1 to 10+ years. For utility patents, the term runs from the filing date. For design patents, from the issue date. This distinction matters significantly for expiration calculations.
Finding Expiration Dates
How do I find a patent's expiration date?
The fastest way is PatentClock's free lookup — enter the patent number and get the calculated expiration date instantly with a full adjustment breakdown. You can also check USPTO's Patent Center for raw data (manual calculation required), or Google Patents for rough estimates (often inaccurate).
Why is the date on Google Patents different from PatentClock?
Google Patents uses estimated expiration dates that frequently don't account for Patent Term Adjustment (PTA), Patent Term Extension (PTE), terminal disclaimers, or maintenance fee lapses. PatentClock calculates using actual data from the USPTO's PatentsView API with all known adjustments factored in.
Can I check if maintenance fees have been paid?
Yes. USPTO's Patent Center shows maintenance fee payment history. PatentClock also factors maintenance fee status into its calculations, flagging whether a patent has lapsed due to non-payment.
Adjustments & Extensions
What is Patent Term Adjustment (PTA)?
Extra time added to compensate for USPTO delays during examination. If the office takes longer than guaranteed timelines, the patent owner receives additional days — ranging from zero to several years. PTA is reduced by any delays caused by the applicant.
What is Patent Term Extension (PTE)?
Additional patent term under 35 U.S.C. § 156 to compensate for FDA regulatory review time. Applies to drugs, biologics, medical devices, food additives, and veterinary products. Can add up to 5 years, with total remaining term capped at 14 years from FDA approval.
What is a terminal disclaimer?
A voluntary agreement to shorten a patent's term so it expires on the same date as a related earlier patent. Filed to overcome obviousness-type double patenting rejections. The result: the later patent expires when the earlier one does, regardless of its own filing date — potentially years earlier than expected.
How do continuations affect expiration?
Continuations, divisionals, and CIPs share the filing date of the parent application for term purposes. A continuation filed in 2020 based on a 2012 parent has its 20-year term measured from 2012, not 2020 — significantly shortening the effective term.
Maintenance Fees & Early Expiration
What are patent maintenance fees?
US utility patents require payments at 3.5, 7.5, and 11.5 years after issuance ($2,000, $3,760, and $7,700 for large entities). Non-payment causes premature expiration. About 50% of all US patents expire before their full term due to this. Design and plant patents don't require maintenance fees.
Can a patent expire early?
Yes — most commonly from non-payment of maintenance fees. Also from terminal disclaimers, or invalidation through inter partes review (IPR), post-grant review (PGR), or court litigation.
Can an expired patent be renewed?
If it expired from missed maintenance fees, it can sometimes be revived by paying the overdue fee plus a surcharge, with a petition showing unintentional delay. Once a patent expires at the end of its natural term (20 years + adjustments), it cannot be renewed or extended.
Special Cases
How are design patents different?
Design patents filed on or after May 13, 2015 last 15 years from the issue date (not filing date). Earlier design patents last 14 years. No maintenance fees are required — they don't expire early from non-payment.
What about pre-1995 patents?
Patents filed before June 8, 1995 use the longer of: (a) 17 years from the issue date, or (b) 20 years from the filing date. This transitional rule makes these patents trickier to calculate.
Still Have Questions?
Try looking up a patent yourself — see exactly how the expiration date is calculated with a full adjustment breakdown.