A granted U.S. utility patent lasts 20 years from the earliest U.S. non-provisional filing date it can claim, under 35 U.S.C. § 154(a)(2) — not 20 years from grant, and not from any provisional application that preceded it. That baseline term can then move in either direction: it shortens if the periodic maintenance fees required to keep it in force under 35 U.S.C. § 41(b) go unpaid, it lengthens through patent term adjustment (PTA) when the USPTO itself causes prosecution delay, and — for a narrow category of drug, biologic, medical device, and food/color additive patents — it can lengthen further through patent term extension (PTE) to offset time spent in regulatory review. This guide covers all four mechanics: the 20-year statutory term, the maintenance-fee schedule that keeps a utility patent alive, PTA, and PTE. It does not cover provisional patent applications or the 12-month provisional pendency clock — see CASRAI’s separate guide on provisional patent applications for that distinct topic.
The short answer, by patent type
The United States grants three kinds of patents, and they run on two different clocks. Only utility and plant patents use the 20-years-from-filing rule in § 154(a)(2); design patents run on a separate, grant-based term under a different statute.
| Patent type | Term | Measured from | Statutory basis | Maintenance fees? |
|---|---|---|---|---|
| Utility patent | 20 years | Earliest U.S. non-provisional filing date | 35 U.S.C. § 154(a)(2) | Yes — required at 3.5, 7.5, and 11.5 years after grant |
| Plant patent | 20 years | U.S. filing date | 35 U.S.C. § 154(a)(2) | No |
| Design patent | 15 years | Date of grant | 35 U.S.C. § 173 | No |
Most of what makes patent term a genuinely complicated question — maintenance fees, PTA, PTE — applies only to utility patents. Design and plant patents are simpler: once granted, no further USPTO fee is owed to keep either in force for its full statutory term (35 U.S.C. § 41(b) expressly states “no fee may be established for maintaining a design or plant patent in force”).
Utility patent term: 20 years from the earliest non-provisional filing date
Under 35 U.S.C. § 154(a)(2), a utility patent’s term “begin[s] on the date on which the patent issues and end[s] 20 years from the date on which the application for the patent was filed in the United States.” Two details in that sentence do most of the practical work:
- The clock starts at filing, not at grant. Because USPTO examination (prosecution) routinely takes one to three-plus years, the effective in-force period after a patent actually issues is almost always shorter than 20 years — often by several years, before any adjustment is applied.
- “Earliest” filing date can reach back through a claimed priority chain. If the application contains a specific reference to an earlier-filed U.S. application under 35 U.S.C. §§ 120, 121, 365(c), or 386(c) — the provisions governing continuations, divisionals, and certain international-to-national-stage claims — the 20-year term is measured from that earlier filing date, not the date the current application itself was filed. A patent issuing from a third continuation in a family can therefore expire on the same date as its original parent application, 20 years out, even though it was filed years later.
The statute also specifies what does not pull the start date backward: “Priority under section 119, 365(a), 365(b), 386(a), or 386(b) shall not be taken into account in determining the term of a patent.” Section 119(e) is exactly the provision a non-provisional application uses to claim the benefit of an earlier-filed provisional application — so a provisional filing date never starts the 20-year clock, and the 12-month provisional pendency period is effectively “free” time that doesn’t count against the eventual patent’s term. See CASRAI’s guide to provisional patent applications for how that filing type and its 12-month deadline work; this guide picks up from the non-provisional filing date the 20-year term actually runs from.
Worked example (illustrative arithmetic, not a real patent): a non-provisional utility application filed March 1, 2024 — whether or not it claims benefit of an earlier provisional — has a term that, absent any adjustment, ends March 1, 2044. If that same application had instead been filed as a continuation claiming priority under § 120 to a parent application filed March 1, 2021, its term would end March 1, 2041, regardless of when the continuation itself was filed.
Maintenance fees: what it actually takes to keep a utility patent in force
A granted utility patent does not stay in force automatically for its full term. Under 35 U.S.C. § 41(b), the USPTO charges three maintenance fees, due at fixed points measured from the grant date (not the filing date): 3.5 years, 7.5 years, and 11.5 years after issuance. Missing all three payment windows, including their grace periods, causes the patent to expire early — years or even a decade-plus before the full 20-year statutory term would otherwise run out.
Each fee can be paid without surcharge during a six-month window ending at the 4-, 8-, and 12-year marks, or paid late with a surcharge during a further six-month grace period after that. The dollar amounts the USPTO actually charges are set under its fee-setting authority (rather than the older amounts printed directly in the statute) and currently stand as follows, per the USPTO fee schedule (effective January 19, 2025, last revised July 1, 2026):
| Due window | Large entity | Small entity | Micro entity |
|---|---|---|---|
| 3.0–3.5 years after grant | $2,150 | $860 | $430 |
| 7.0–7.5 years after grant | $4,040 | $1,616 | $808 |
| 11.0–11.5 years after grant | $8,280 | $3,312 | $1,656 |
A late payment made during the six-month grace period after each due date carries a flat $540 surcharge regardless of entity size. If a patent lapses for non-payment even after the grace period, the owner can petition to revive it only on a showing that the delay was unintentional (or, for older lapses, unavoidable), paying an additional petition fee on top of the overdue maintenance fee and surcharge. Entity size — large, small, or micro — is a separate USPTO determination based on the applicant’s size and prior patenting/licensing activity, not something this guide sets out to define; verify current status before relying on the small- or micro-entity rate for a specific patent.
Because these fees escalate sharply at each tier, maintenance-fee decisions are a real, recurring portfolio-management task for a technology transfer office: a patent with no active licensee and no near-term commercial prospect is a legitimate candidate for deliberate abandonment at the 11.5-year mark rather than a $8,280-and-up commitment to carry it to expiration.
Patent term adjustment (PTA): extra days for the USPTO’s own delays
Patent term adjustment, under 35 U.S.C. § 154(b), adds days back onto the 20-year term when the USPTO itself is responsible for prosecution delay. It was created by the American Inventors Protection Act of 1999 specifically so that USPTO backlog and processing delay would not eat into the patent owner’s guaranteed 20 years. PTA is calculated automatically and printed on the face of the issued patent; it is not something an applicant has to separately request in the ordinary case.
PTA accrues under three overlapping guarantees, and the USPTO’s own Patent Term Guarantee overview summarizes them as:
- “A” delay — USPTO response deadlines. The USPTO must take specific actions within fixed windows (for example, a first office action within 14 months of filing, a response to an applicant’s reply within 4 months, issuance within 4 months of the issue fee being paid). Each day the USPTO misses one of these deadlines generally adds a day of PTA.
- “B” delay — the three-year guarantee. If the USPTO fails to issue a patent within three years of the application’s actual U.S. filing date, PTA accrues for each day beyond that three-year mark — subject to specific carve-outs (time consumed by a request for continued examination, secrecy orders, interferences, appeals, and applicant-requested delays does not count toward the three years).
- “C” delay — interference, secrecy order, and successful appeal delay. Time lost to a patent interference proceeding, a secrecy order, or a successful appeal to the Patent Trial and Appeal Board or a reviewing court adds day-for-day PTA, with no statutory cap.
Two mechanics matter for anyone reading a PTA figure off a granted patent: overlapping delays under different guarantees are counted only once (a day of delay that qualifies under both “A” and “B” adds one day of PTA, not two), and PTA is reduced by any period of applicant delay — most commonly time an applicant takes beyond three months to respond to an office action. Filing a request for continued examination (RCE) also cuts off further PTA accrual under the “B” three-year guarantee from that point forward, even though USPTO delay after the RCE can still accrue “A”-type PTA. Because of this, RCE strategy is a real PTA consideration for any patent prosecution likely to run close to its statutory deadlines.
Patent term extension (PTE): extra years for regulatory-approval delay
Patent term extension, under 35 U.S.C. § 156, is a different mechanism from PTA, created by the Drug Price Competition and Patent Term Restoration Act of 1984 (commonly known as the Hatch-Waxman Act). It compensates patent owners for time a product spent in mandatory regulatory review — most notably FDA review — before it could be commercially marketed, on the reasoning that time spent proving a drug or device safe and effective, rather than in USPTO prosecution, was otherwise unrecoverable patent life.
PTE applies to a patent claiming a product, or a method of using or manufacturing a product, that went through regulatory review under specific federal frameworks before commercial marketing — chiefly new human drugs, antibiotics, and biologics under the Federal Food, Drug, and Cosmetic Act and the Public Health Service Act, but also medical devices, food and color additives, and new animal drugs and veterinary biologics subject to their own review processes. Key constraints:
- Only one patent per approved product may receive a PTE, and only one claim covering the approved product, an approved method of using it, or an approved method of manufacturing it is extended — not an entire patent family.
- The application deadline is strict: it must be filed within 60 days of the date the product receives permission for commercial marketing or use.
- The extension is capped at 5 years beyond the patent’s original (unextended, but PTA-adjusted where applicable) expiration date.
- A hard 14-year ceiling applies: the remaining patent term as of the product’s approval date, plus the extension granted, cannot together exceed 14 years from that approval date — so a patent that issued late and already has relatively little remaining term at approval can still be capped well short of the full 5-year maximum.
- Interim extensions of up to five one-year periods are available if regulatory review is still pending when the unextended patent term is about to expire, to bridge the gap until final approval and the full PTE calculation can be made.
For research institutions and their technology transfer offices, PTE is most relevant when a university-owned or university-licensed patent covers a compound, biologic, or device that a licensee is taking through FDA approval — the extension calculation, and the 60-day filing deadline that triggers it, is typically the licensee’s or its patent counsel’s responsibility, but a TTO tracking a licensed patent’s real expiration date needs to know PTE exists and roughly what it can and can’t add. See CASRAI’s clinical research administration content for the regulatory-approval side of this timeline.
Design and plant patents: different clocks, and no maintenance fees at all
Design patents — which protect a product’s ornamental appearance rather than how it functions — run for 15 years from the date of grant under 35 U.S.C. § 173 (applications filed on or after May 13, 2015; 14 years from grant for the small remaining population of earlier design patents). Plant patents, which protect a distinct and new asexually reproduced plant variety, use the same 20-years-from-filing rule as utility patents under § 154(a)(2). Neither type is subject to PTA or PTE, and — as noted above — neither requires any maintenance fee to stay in force for its full statutory term. A design or plant patent that issues simply runs to its fixed expiration date with no further USPTO payment required.
What happens when a patent expires
When a patent’s term ends — whether by running its full statutory course, lapsing for an unpaid maintenance fee, or being invalidated — the invention falls into the public domain. Anyone can then make, use, sell, or import what the claims covered without the former owner’s permission, and there is no mechanism to renew or extend a utility patent’s term beyond what §§ 154 and 156 already provide once that term has actually run. This is a meaningful contrast with trademarks, which can be renewed indefinitely as long as the mark stays in commercial use, and with copyright, which in the United States generally lasts for the life of the author plus 70 years (or a fixed term of years for certain works made for hire) under Title 17 rather than Title 35 of the U.S. Code.
Frequently asked questions
Does patent term start at filing or at grant?
The 20-year clock for a utility or plant patent starts at the earliest qualifying U.S. filing date, not at grant — but the patent only becomes enforceable once it actually issues. The gap between filing and grant (often one to three-plus years, sometimes longer) is prosecution time that comes out of the 20-year term unless offset by patent term adjustment.
Does the 12-month provisional application period count against the 20 years?
No. Because 35 U.S.C. § 154(a)(2) excludes § 119(e) priority (the provision a non-provisional application uses to claim benefit of an earlier provisional filing) from the term calculation, the 20-year clock starts at the non-provisional filing date, not the earlier provisional filing date. See CASRAI’s provisional patent application guide for how that 12-month window works on its own terms.
Can a patent’s term be renewed once it expires?
No. Unlike a trademark registration, there is no renewal mechanism for an expired utility, design, or plant patent. Once the statutory term (as adjusted by PTA or PTE, where applicable) has run, the invention is permanently in the public domain.
What happens if a maintenance fee payment is missed?
The patent expires at the end of the six-month grace period following the missed due date unless the fee is paid with the applicable surcharge before that grace period ends. After that, the owner can petition to revive the patent only on a showing of unintentional (or unavoidable, for older lapses) delay, along with an additional petition fee.
How is patent term adjustment (PTA) different from patent term extension (PTE)?
PTA (35 U.S.C. § 154(b)) compensates for delay the USPTO itself causes during prosecution and applies to any patent type. PTE (35 U.S.C. § 156) compensates for time a product spent in mandatory regulatory review — chiefly FDA review of drugs, biologics, and devices — before it could be marketed, and applies only to patents covering products subject to that review. A single patent can, in principle, receive both PTA (for USPTO delay) and PTE (for regulatory-review delay), though PTE’s 14-year cap from the product’s approval date limits how much total benefit accrues.
Where can I find a specific patent’s actual expiration date?
The face of an issued U.S. patent states its filing date and, where applicable, its PTA in days (in the “Notice” section near the top of the printed patent). The USPTO’s Patent Public Search and Patent Maintenance Fees systems, and commercial patent-docket tools, can confirm current maintenance-fee status and any PTE granted. Because PTA, PTE, and maintenance-fee status can each shift the real expiration date away from a simple “20 years from filing” calculation, confirming an exact date for a specific patent means checking the patent itself and the USPTO’s records rather than relying on the filing date alone.
Related CASRAI resources
- Provisional Patent Applications: USPTO Requirements, Cost, and the 12-Month Deadline — the distinct 12-month provisional pendency period, which precedes and does not count against the 20-year term covered here
- 35 U.S.C. § 102: Patent Novelty and Invention Disclosure Timing — the disclosure and filing-date rules that determine when a patent’s term begins running
- Patent — CASRAI Dictionary object template for recording patent metadata
- Clinical Research Administration — the regulatory-approval timelines relevant to patent term extension for drug and device patents
- Technology Transfer & Innovation — the full tech-transfer cluster
This guide explains the general USPTO framework governing utility, design, and plant patent term under 35 U.S.C. §§ 41, 154, 156, and 173. It is not legal advice; a specific patent’s actual current expiration date depends on its individual prosecution history, maintenance-fee payment status, and any PTA or PTE granted, and should be confirmed with qualified patent counsel or directly against USPTO records.
