Patent Term Calculator

The basic term for US utility patents is set by 35 U.S.C. § 154(a)(2): BASE RULE: a utility patent expires 20 years from the earliest effective US filing date; EARLIEST EFFECTIVE US FILING DATE: this is the earliest US non-provisional application whose benefit is claimed; it is NOT necessarily the application that issued as the patent; EXAMPLE: if a continuation application was filed in 2023 claiming benefit of a parent filed in 2018, the patent expires 20 years from 2018 (2038) — not 20 years from the continuation's filing date (2043); CLAIMING BENEFIT: the 20-year clock starts from the date the first US application in the chain was filed; CIP (continuation-in-part) applications: only claims that are entitled to benefit of the parent's filing date get the parent's priority date — new matter claims may use the CIP's own filing date; FOREIGN PRIORITY DOES NOT AFFECT THE TERM: Paris Convention priority to a foreign application does NOT move the 20-year clock; only the US filing date matters for US patent term; PRE-GATT PATENTS: patents with applications filed before June 8, 1995 (GATT implementation date) get the LONGER of (a) 17 years from issue date OR (b) 20 years from earliest filing date; very few such patents are still in force; DESIGN PATENTS: different rule — 15 years from issue date (changed from 14 years for applications filed after May 13, 2015); PLANT PATENTS: 20 years from filing date; PROVISIONAL APPLICATIONS: do NOT count for the 20-year term; a provisional's 12-month period doesn't burn patent term.

Patent Term Adjustment under 35 U.S.C. § 154(b) adds days to the patent term to compensate for USPTO delays during examination: THREE TYPES OF PTA ADJUSTMENTS: (A) GUARANTEE OF PROMPT USPTO ACTION (Type A): USPTO failed to take any of these actions within specified timeframes — (1) issue a first Office Action within 14 months of filing; (2) respond to applicant reply within 4 months; (3) act on appeal decision, IFW, or allowance within 4 months; (4) issue a patent within 4 months of issue fee payment; each day of delay adds 1 day of PTA; (B) GUARANTEE OF NO MORE THAN 3-YEAR APPLICATION PENDENCY (Type B): if the application takes more than 3 years from US filing to patent issuance (excluding certain periods), the excess days are added; (C) GUARANTEE OF ADJUSTMENTS FOR DELAYS DUE TO SECRECY ORDERS, INTERFERENCE, AND APPEALS: additional adjustments; APPLICANT DELAYS REDUCE PTA: any delay caused by the applicant reduces the PTA; common applicant delays that reduce PTA: (1) filing a Request for Continued Examination (RCE) — entire RCE period (from RCE filing to resumption of examination) is applicant delay; (2) late replies (after the 3-month shortened statutory period); (3) petitions and appeals triggered by applicant; (4) amendments that introduce new issues requiring further examination; NET PTA: PTA = USPTO delays minus applicant delays; READING PTA ON THE PATENT: the PTA is printed on the face of the patent and in the USPTO patent database; actual expiration date = 20 years from earliest US filing date + PTA days; CHALLENGING PTA: applicants can petition to correct PTA calculations; requests must be filed within 2 months of patent issue.

A terminal disclaimer is a patent office filing that voluntarily limits a patent's term, typically to address obviousness-type double patenting rejections: PURPOSE: prevents an applicant from extending patent protection on the same invention by filing continuation applications; when a continuation application claims subject matter that is obvious in view of an earlier family member, the USPTO issues an obviousness-type double patenting rejection; the applicant files a terminal disclaimer to overcome the rejection; WHAT A TERMINAL DISCLAIMER DOES: (1) SHORTENS TERM: the disclaimed patent's term cannot extend beyond the term of the earlier patent it is terminally disclaimed over; the expiring patent terminates when its reference patent terminates, even if the disclaimed patent would otherwise run longer; (2) COMMON OWNERSHIP REQUIREMENT: terminal disclaimer requires that the disclaimed patent and its reference patent remain commonly owned for their entire term; if they are assigned to different owners, the patent is unenforceable; CALCULATING EXPIRATION WITH TERMINAL DISCLAIMER: the expiration date of a patent with a terminal disclaimer = the EARLIER of (a) 20 years from earliest US filing date + PTA; or (b) the expiration date of the reference patent in the terminal disclaimer; TERMINAL DISCLAIMER + PTA INTERACTION: in 2025, the USPTO issued new rules significantly restricting PTA for patents with terminal disclaimers — applicants can no longer fully accumulate PTA on heavily continued applications; TERMINAL DISCLAIMER INVALIDITY: Allergan v. MSN Laboratories (Fed. Cir. 2025 en banc): raised questions about terminal disclaimer enforceability in ODP analysis — watch for further developments; WHY THIS MATTERS FOR VALIDITY: terminal disclaimers are required to be filed as a condition of grant; if the common ownership requirement is later violated, the patent is unenforceable.

Patent Term Extension under 35 U.S.C. § 156 restores patent term lost during regulatory review by the FDA or other federal agencies: PURPOSE: pharmaceutical, food additive, medical device, veterinary biological, and animal drug patents may lose significant term while waiting for FDA approval; PTE compensates for this regulatory review time; WHO QUALIFIES: (1) the patent must claim either the approved product, the method of using it, or the method of manufacturing it; (2) the product must have received its first FDA regulatory review (NDA, BLA, PMA, etc.); (3) the product must not have been commercially marketed in the US before the FDA approval; (4) the application for PTE must be timely filed (within 60 days of FDA approval); CALCULATION OF PTE: the PTE period = 1/2 of the IND (Investigational New Drug) testing period + full NDA review period; maximum PTE = 5 years; the remaining term after PTE cannot exceed 14 years from the date of approval; MAXIMUM TERM AFTER PTE: final patent term = original expiration date + PTE, but capped at 14 years of remaining term from FDA approval; ONLY ONE PATENT PER PRODUCT: only one patent per approved product can receive PTE; applicants must choose which patent to extend if multiple qualify; ORANGE BOOK: FDA-listed patents in the Orange Book (for approved drugs) typically receive or have applied for PTE; COMPARISON WITH PATENT TERM ADJUSTMENT: PTA compensates for USPTO prosecution delays; PTE compensates for FDA regulatory delays; they are separate; a patent can theoretically receive both; BIOLOGICS: Biologics License Applications (BLAs) qualify for PTE; biosimilar exclusivities (12-year exclusivity) are separate from PTE.

Calculating the actual expiration date of a US patent requires checking multiple adjustments: STEP 1 — FIND THE EARLIEST EFFECTIVE US FILING DATE: locate the patent's priority chain; find the earliest US non-provisional application whose benefit is claimed; this is the start date for the 20-year term; STEP 2 — CALCULATE BASE EXPIRATION DATE: add 20 years to the earliest US filing date; STEP 3 — ADD PATENT TERM ADJUSTMENT (PTA): the PTA amount in days is printed on the face of the issued patent; add the PTA days to the base expiration date; check USPTO PAIR (Patent Application Information Retrieval) or the patent itself for the exact PTA; STEP 4 — CHECK FOR TERMINAL DISCLAIMERS: search the patent's prosecution history for terminal disclaimers; if a terminal disclaimer was filed, the expiration is the EARLIER of the adjusted date (Step 3) or the expiration of the reference patent; STEP 5 — CHECK FOR PATENT TERM EXTENSION (PTE): for pharmaceutical, medical device, or food/drug additive patents, check if a § 156 PTE was granted; the PTE amount is stated in the USPTO patent database and on the patent; add the PTE to the adjusted date; STEP 6 — VERIFY WITH USPTO: the USPTO website (patft.uspto.gov or Google Patents) now shows a calculated expiration date for all in-force patents; always cross-check your manual calculation; PRACTICAL TOOLS: Google Patents shows expiration dates; the USPTO Patent Center shows PTA and prosecution history; the Orange Book (for pharma) shows PTE; IMPORTANT CAVEAT: patents can be invalidated (IPR, litigation) or unenforceable before their expiration; an expiration date reflects the maximum potential term, not a guarantee of enforceability.