How long can a patent last is a different question from how long a patent usually lasts, and the answer is longer than most people expect.
The base is twenty years from the non-provisional filing date.
Three things add to it, and one of them can add five years.
Stack everything available and the protected period from first filing runs to around 26 years. Almost nothing gets there. It requires a pharmaceutical or medical device patent that lost substantial time to both USPTO examination and FDA review, which is a narrow set.
What can be added to the 20 years
| Addition | Adds | Who can get it |
|---|---|---|
| Provisional year | Up to 12 months of protection before the clock starts | Anyone who files a provisional first |
| Patent Term Adjustment | 0 to 1,000+ days | Any patent delayed by the USPTO |
| Patent Term Extension | Up to 5 years | Pharma and medical devices only, one per product |
Only PTA and PTE extend the term itself. The provisional year is different — it does not lengthen the patent, it adds a protected period in front of it, because the 20-year clock runs from the non-provisional filing rather than the provisional.
Nothing else adds time. No renewal, no refiling, no continuation, no payment.
| Common misconception | Reality |
|---|---|
| "Renew the patent at 20 years" | No renewal exists. Maintenance fees keep it alive within term |
| "File a continuation to extend it" | Continuations expire with the parent |
| "Pay more to keep it longer" | Fees never buy term |
| "Improve it and refile" | A new patent on a new invention, not an extension |
The maximum, stacked
Take a pharmaceutical patent with everything running long.
| Stage | Date | Effect |
|---|---|---|
| Provisional filed | Jan 2010 | Priority secured, no term consumed |
| Non-provisional filed | Jan 2011 | 20-year clock starts |
| Base expiry | Jan 2031 | 20 years |
| Patent Term Adjustment | +730 days | Jan 2033 |
| Granted | Jun 2015 | — |
| FDA approval | Mar 2022 | PTE eligibility |
| Patent Term Extension | +5 years | Jan 2038 |
| PTE cap check | 14 years from Mar 2022 = Mar 2036 | Capped at Mar 2036 |
| Final expiry | Mar 2036 | |
| Total protected from first filing | Jan 2010 → Mar 2036 | ~26 years |
The cap bites. PTE was worth five years on paper but the 14-years-from- approval ceiling cut it to about three. That cap is what stops long FDA reviews producing indefinite protection.
Two thirds of that is ordinary. The 20 years plus the provisional year is available to anyone. Only the last stretch requires the pharmaceutical route.
Patent Term Adjustment: the one most patents can use
PTA is automatic and applies to any technology. It compensates for USPTO delay under 35 U.S.C. 154(b), and it is printed on the front page of the patent.
| Delay type | What triggers it |
|---|---|
| A delay | First office action beyond 14 months; other response deadlines missed by the Office |
| B delay | Issuance beyond three years from filing |
| C delay | Time lost to interferences, secrecy orders, or successful appeals |
| Applicant delay | Subtracted — extensions of time, late responses, late IDS filings |
Applicant delay is subtracted day for day. Every extension of time you take comes off the adjustment. An applicant who routinely responds in month five rather than month two can eliminate their entire PTA.
Overlapping A and B delay is not double-counted. The statute prevents the same period being credited twice, which is the most common source of disputes over a PTA figure.
Check the number and dispute it if wrong. A request for reconsideration must be filed within two months of grant. See patent term adjustment for the calculation and the challenge process.
Patent Term Extension: the five-year addition
PTE exists because FDA review consumes patent term while the product cannot be sold. Hatch-Waxman restores part of it.
| Rule | Detail |
|---|---|
| Maximum | 5 years |
| Hard cap | 14 years of remaining term from FDA approval |
| Eligible patents | Pharmaceuticals, medical devices, food and colour additives |
| How many | One patent per approved product |
| Calculation | Half the testing phase plus all of the review phase |
| Deadline | Application within 60 days of approval |
One patent per product is the constraint that shapes pharmaceutical strategy. A drug covered by a composition patent, a formulation patent and a method-of- treatment patent can extend only one. Choosing which is a significant commercial decision made under a 60-day deadline.
The 60-day window is unforgiving. Miss it and the extension is gone regardless of entitlement.
Europe has an equivalent. Supplementary Protection Certificates operate similarly for pharmaceutical and plant protection products, also up to five years, with their own calculation.
Terminal disclaimers cut the other way
A terminal disclaimer permanently shortens a patent to match an earlier related one, and it is the most common reason a patent lasts less than its arithmetic allows.
It is filed to overcome obviousness-type double patenting — where claims are unpatentable over an earlier patent by the same inventor or owner, even though your own patent is not prior art against you.
| What the disclaimer does | Effect |
|---|---|
| Surrenders term beyond the earlier patent | The later patent expires with the earlier |
| Requires common ownership | The two cannot be sold separately |
| Is not reversible | Permanent once filed |
The common ownership requirement matters at sale. Two patents tied by a terminal disclaimer must stay in the same hands to remain enforceable, which removes the option of selling one and keeping the other.
The pre-1995 rule and submarine patents
Patents filed before 8 June 1995 ran 17 years from grant. Because the clock started at grant rather than filing, prosecution time did not consume term — it deferred it.
That produced submarine patents. An applicant could keep an application pending for years through continuations, watch an industry adopt the technology, then allow the patent to issue and start a fresh 17-year term against a mature market.
| Pre-1995 | Post-1995 | |
|---|---|---|
| Term runs from | Grant | Filing |
| Length | 17 years | 20 years |
| Effect of slow prosecution | Deferred the term | Consumes the term |
| Submarine strategy | Viable | Eliminated |
The 1995 change was designed to kill that strategy, and it did. Under the current rule, delay costs term rather than banking it — which is precisely why PTA exists to compensate for delay that was not the applicant's fault.
Applications pending on 8 June 1995 got the longer of the two terms, which is why a small number of mid-1990s patents have expiry dates that look wrong under either rule alone.
Why almost nothing reaches the maximum
The ceiling is legal. The floor is economic.
| Ipiry Patent Survival Curve v1.0 | Rate |
|---|---|
| Survive the 3.5-year fee (2022 cohort) | 85.8% |
| Survive the 7.5-year fee (2018 cohort) | 64.6% |
| Reach full term (2014 cohort) | 41.4% |
| Abandoned before full term | 58.6% |
| Peak full-term rate (2000 cohort) | 51.1% |
Computed from 27,273,654 USPTO maintenance fee records covering 8,262,336 US utility patents. Full dataset at the patent survival curve.
Even at the historical peak, only half made it. The 2000 cohort reached 51.1%, the best figure in the dataset. Most patents have never lasted their full term, in any era.
The third maintenance fee is where the maximum is usually abandoned. At $8,280 for a large entity, falling due with roughly eight years left, it is the point where owners most often conclude the remaining window is not worth buying.
Which means "how long can a patent last" and "how long will this patent last" have very different answers for the same document. See how long will a patent last for calculating the second.
Term extension outside the US
Most major jurisdictions have an equivalent to PTE, under different names and with different arithmetic.
| Jurisdiction | Mechanism | Maximum |
|---|---|---|
| United States | Patent Term Extension (Hatch-Waxman) | 5 years, capped at 14 from approval |
| Europe | Supplementary Protection Certificate | 5 years, capped at 15 from first authorisation |
| Europe (paediatric) | SPC paediatric extension | +6 months on top |
| Japan | Patent term extension | 5 years |
| South Korea | Patent term extension | 5 years |
| Most other countries | None | — |
Europe's SPC is technically a separate right, not an extension of the patent itself, though it operates the same way commercially. It is granted per country rather than centrally, so a pharmaceutical product needs SPCs filed in each market where protection matters.
The paediatric extension is worth knowing about. Completing an agreed paediatric investigation plan adds six months to an SPC — small in percentage terms, large in absolute revenue on a successful drug.
Europe also compensates for office delay differently. There is no general equivalent to US Patent Term Adjustment at the European Patent Office; slow examination simply consumes term.
Which means a family's maximum term varies by country on identical technology. The US patent may run years longer than the European one, or the reverse where an SPC applies and PTA did not.
What the maximum is worth
Term is a multiplier, not a value. A long-lived patent covering technology nobody practises is worth close to nothing, however many years it has.
But term multiplies everything else, because enforcement takes years.
| Years remaining | What is realistically achievable |
|---|---|
| 15+ | Full licensing programme; litigation to judgment with time to spare |
| 10–15 | Licensing campaign; litigation viable |
| 7–10 | Assertion workable where infringement is clear |
| 5–7 | Tight — a contested case may outlast the patent |
| Under 5 | Most disputes will not conclude in time |
Litigation to judgment routinely takes three to five years. A patent with four years left may expire mid-case, which limits remedies to past damages and removes injunctive leverage entirely.
This is why the extra years from PTA and PTE are disproportionately valuable. Adding two years to a patent with fifteen left changes little; adding two years to one with five left can be the difference between an assertable asset and an expiring one.
And it is why the maximum-term question is really a valuation question. See how long will a patent last for calculating the remaining life on a specific patent rather than the ceiling.
Patent term and the public domain
Expiry is absolute and irreversible. When a patent's term ends, the claimed invention enters the public domain permanently and anyone may practise it without permission or payment.
| After expiry | Position |
|---|---|
| Anyone may make, use, sell, import | Yes |
| Former owner can object | No |
| Royalties may continue | No — patent misuse |
| Revival possible | Only for fee lapse, never for term expiry |
| Marking products as patented | False marking exposure |
Term expiry and fee lapse are different endings. A patent that lapsed for an unpaid fee can sometimes be revived by petition under 37 CFR 1.378. A patent that reached the end of its term cannot be revived by any mechanism at all.
Continuing to mark products with an expired patent number carries risk. False marking is actionable where there is intent to deceive, and the safest practice is a virtual marking page that is actually maintained.
The public domain is also an asset. Expired patents are freely usable technology, professionally documented, with a written record of what was tried. Nearly three in five US utility patents end up there before their term even runs.
Extending coverage without extending term
Term cannot be extended beyond the rules above. Coverage can.
| Mechanism | What it achieves | Effect on term |
|---|---|---|
| Continuation | New claims from the same disclosure | None — expires with the parent |
| Divisional | Pursues claims to a restricted-out invention | None |
| Continuation-in-part | Adds new matter; new matter gets a later priority date | New matter runs from the CIP filing |
| Reissue | Corrects a defective patent | Cannot exceed the original term |
| New application on an improvement | A genuinely new invention | Own full 20-year term |
Continuations are how portfolios stay relevant, not how patents last longer. A continuation kept pending lets you write claims aimed at what a competitor actually built once you can see it — but it expires the same day as its parent.
Continuation-in-part is the one that can reach further. New matter added in a CIP gets the CIP's filing date, so claims supported only by that new matter run 20 years from then. Claims supported by the original disclosure keep the earlier date. A single CIP patent can therefore have claims with different effective dates.
File the continuation before the parent issues. Once the parent grants with nothing pending behind it, the family is closed permanently and the option is gone.
How long can a patent last: the checklist
- Start from the non-provisional filing date. Not the provisional, not the grant date.
- Add twenty years for a utility patent, or take 15 years from grant for a design patent.
- Add the Patent Term Adjustment printed on the front page. This is available to any technology and is frequently substantial.
- Subtract applicant delay if you are estimating PTA before grant — every extension of time taken reduces it day for day.
- Check PTE eligibility only if the patent covers a pharmaceutical, medical device, or food or colour additive. Up to five years, capped at 14 from approval.
- File the PTE application within 60 days of FDA approval. The window does not reopen.
- Choose which patent gets PTE deliberately. Only one per approved product, and the choice cannot be revisited.
- Check for a terminal disclaimer. It overrides the arithmetic and ties the patent to an earlier one in common ownership.
- Confirm the pre-1995 rule does not apply. Anything filed before 8 June 1995 ran 17 years from grant instead.
- Then check maintenance fee status, because the maximum is irrelevant if the patent has already lapsed — and 58.6% of them do.