Patent term adjustment is the mechanism that gives back time the USPTO took. A utility patent runs twenty years from its earliest non-provisional filing date — see how long does a patent last — so every month of examination is a month of enforceable life consumed — and where the delay was the Office's fault, 35 U.S.C. 154(b) adds it back.
Most owners never look at it. The figure is printed on the face of the patent and the window to challenge it is two months. On a patent that spent four years in prosecution, PTA can be worth a year or more of additional exclusivity, which is a substantial asset to leave unchecked.
Why PTA exists
Before 1995, US patents ran seventeen years from grant. Examination delay cost the applicant nothing — a patent that took six years to issue simply issued later and still ran seventeen years.
The switch to twenty years from filing changed the incentive entirely. Under the current rule, every month in examination is a month gone. An applicant whose patent sat awaiting a first action for three years lost three years of term through no fault of their own.
PTA is the correction. It restores time lost to Office delay while leaving applicants to bear the cost of their own.
The three delay categories
The statute defines three types of Office delay, referred to in practice as A, B and C.
| Type | What it covers | Statutory basis |
|---|---|---|
| A delay | Missed specific deadlines during prosecution | 35 U.S.C. 154(b)(1)(A) |
| B delay | Total pendency beyond three years | 35 U.S.C. 154(b)(1)(B) |
| C delay | Interference, secrecy order, successful appeal | 35 U.S.C. 154(b)(1)(C) |
A delay: the fourteen-month guarantee and its siblings
The Office commits to specific response times, and misses them frequently.
| Office obligation | Deadline |
|---|---|
| First office action, or notice of allowance | 14 months from filing |
| Reply to an applicant response | 4 months |
| Action after a Board decision | 4 months |
| Issue the patent after the issue fee is paid | 4 months |
Each day beyond these adds a day of A delay. The fourteen-month first action guarantee is the one most commonly missed — average first-action pendency was 19.9 months in FY2024, meaning the typical application accrues roughly six months of A delay before examination even begins.
B delay: the three-year guarantee
If the patent does not issue within three years of filing, every additional day counts — with exclusions for time consumed by continued examination, appeals and interferences.
Total pendency averaged 26.3 months in FY2024, so many patents never reach the three-year threshold. Those that do, typically because of multiple office actions or a Request for Continued Examination, can accrue substantial B delay.
C delay: interference, secrecy and appeals
Time spent in an interference proceeding, under a secrecy order, or in a successful appeal is added. A successful appeal is the significant one — an applicant who appeals a rejection and wins gets the appeal period back, which can be years.
An unsuccessful appeal earns nothing. The time is lost, which is part of the calculus when deciding whether to appeal or file a continuation.
Overlap
A and B delay that occur on the same days are counted once. This was the central question in Wyeth v. Kappos (Fed. Cir. 2010), which corrected the Office's earlier practice of treating the two as alternatives rather than cumulative. Patents granted before that decision were frequently under-credited.
Applicant delay: the part you control
Every day of applicant delay reduces the adjustment day for day, under 37 CFR 1.704. This is the only component of the calculation entirely within the applicant's hands.
| Applicant conduct | Delay charged |
|---|---|
| Responding to an office action after 3 months | Every day beyond 3 months |
| Filing a preliminary amendment requiring a supplemental action | The supplemental action period |
| Abandoning and reviving | The full lapse |
| Filing a supplemental reply | The resulting delay |
| Submitting an IDS after a first action, without the safe harbour statement | The delay caused |
Extensions of time are the biggest single cause. A response filed at month six rather than month three costs ninety days of adjustment. Taking the full extension on every response across a four-year prosecution can eliminate the adjustment entirely — a patent that accrued 400 days of Office delay and 400 days of applicant delay receives nothing.
This is a real cost of routine practice. Firms that default to filing at the extended deadline are trading term for convenience, and on a commercially important patent the trade is a poor one.
A worked example
An application filed 12 March 2015, granted 18 June 2019 — a total pendency of four years and three months.
| Event | Date | Delay accrued |
|---|---|---|
| Filing | 12 Mar 2015 | — |
| First action due (14 months) | 12 May 2016 | — |
| First action actually mailed | 20 Nov 2016 | 192 days A delay |
| Response due (3 months) | 20 Feb 2017 | — |
| Response filed | 18 May 2017 | −87 days applicant delay |
| Final rejection | 3 Oct 2017 | — |
| RCE filed | 2 Jan 2018 | — |
| Three-year mark | 12 Mar 2018 | B delay begins |
| Notice of allowance | 14 Feb 2019 | — |
| Issue | 18 Jun 2019 | — |
Illustrative net adjustment: 192 days of A delay, plus B delay for the period after the three-year mark not excluded by the RCE, less 87 days of applicant delay from the late response.
The 87 days matters. That single extension — one response filed at the extended deadline rather than on time — cost nearly three months of exclusivity at the end of the patent's life, when the technology may be at its most valuable.
And note what the RCE did. Filing a Request for Continued Examination stops B delay accruing for the period of continued examination. It is often the right prosecution decision and it has a term cost.
How to find and check your PTA
On the patent itself. The front page bibliographic data includes a line under 35 U.S.C. 154(b) stating the number of days of extension. It sits near the filing date and application number, and is easy to miss if you are not looking for it.
In Patent Center. The patent's term data shows the calculation components, which is more useful than the total when checking for errors.
What to check:
- Does the first action date match the record, and is the A delay consistent with it?
- Are all applicant delay charges attributable to something you actually did?
- If there was a successful appeal, has C delay been credited?
- If A and B delay overlap, have the overlapping days been counted once rather than subtracted twice?
Errors are not rare. They concentrate in prosecutions involving appeals, multiple RCEs, or long chains of continuations — precisely the applications where the adjustment is largest and therefore worth most.
Disputing the calculation
Request for reconsideration, under 37 CFR 1.705, filed within two months of grant. The period is extendable under 37 CFR 1.136(a), which in practice gives up to seven months, but the two-month date is the one to diarise.
What the request needs: a statement of the correct adjustment, the basis for it, and the fee. The Office reviews and either corrects the determination or maintains it.
District court review. If the Office maintains its position, civil action in the Eastern District of Virginia is available within 180 days of grant under 35 U.S.C. 154(b)(4). Rarely worth it for a small adjustment; occasionally worth it where hundreds of days are at stake on a commercially significant patent.
The window is short and unforgiving. A patent granted today with a PTA error of 200 days has a two-month window in which that is recoverable, after which it is not.
Terminal disclaimers can wipe out PTA
A terminal disclaimer limits a patent's term to that of an earlier related patent. Where PTA would push expiry beyond that date, the disclaimer controls and the adjustment is effectively lost.
This creates a specific trap in continuation practice. A continuation that accrued substantial PTA, then received an obviousness-type double patenting rejection over its parent, may have that adjustment eliminated entirely by the disclaimer filed to overcome it.
Worth weighing before filing the disclaimer. The alternatives — arguing against the rejection, or amending claims — cost prosecution time but may preserve term that is worth more.
PTA versus PTE
The two are separate statutes and frequently confused.
| Patent Term Adjustment | Patent Term Extension | |
|---|---|---|
| Statute | 35 U.S.C. 154(b) | 35 U.S.C. 156 |
| Compensates for | USPTO examination delay | FDA regulatory review |
| Applies to | Any utility or plant patent | One patent per approved product |
| Cap | None, but reduced by applicant delay | 5 years, and 14 years post-approval |
| Automatic | Calculation is | No — must be applied for in 60 days |
| Typical size | Days to hundreds of days | Years |
They stack. A pharmaceutical patent can carry both, which is why some drug patents run well past twenty years from filing.
What PTA does not affect
Maintenance fee deadlines. Fees are due at 3.5, 7.5 and 11.5 years after the grant date regardless of any adjustment. PTA moves the far end of the patent's life; it does not shift the fee schedule.
Priority dates. Adjustment has no effect on the effective filing date for prior art purposes.
Family members. PTA is calculated per patent. A continuation with its own prosecution history has its own adjustment, which may be quite different from its parent's.
Why it matters commercially
Adjustment lands at the end of the patent's life, which is often when it is worth most — after the technology has been adopted, after infringers have emerged, and after the market has developed.
Two hundred extra days of exclusivity on a patent covering a shipping product is a real asset. It is also an asset that affects what the patent is worth in a sale, because a buyer pricing remaining exclusivity is pricing the adjusted expiry date rather than the nominal one.
A patent valuation that ignores term adjustment on a patent with several hundred days of it is understating the asset.
Before you file the next response
- Check the PTA on any patent granted in the last two months — the window closes fast.
- Respond to office actions within three months where you can. Every extension costs adjustment day for day.
- Weigh RCE against appeal on term as well as merits, because an RCE stops B delay accruing.
- Think before filing a terminal disclaimer on a patent carrying meaningful adjustment.
- Verify the calculation components in Patent Center rather than accepting the total.
- Record the adjusted expiry date wherever you track your portfolio — the nominal twenty-year date will be wrong.