Patent Term Adjustment vs Patent Term Extension: Key Differences

Patent Term Adjustment (PTA) and Patent Term Extension (PTE) are two distinct mechanisms for extending a US patent's enforceable life, but they serve different purposes and apply to different situations. PTA, under 35 U.S.C. § 154(b), compensates patent applicants for delays caused by the USPTO during prosecution. PTE, under 35 U.S.C. § 156, compensates patent holders for time lost during FDA regulatory review of products like drugs and medical devices. PTA is calculated automatically by the USPTO and applies to virtually any utility patent. PTE must be separately applied for, applies only to FDA-regulated products, and is subject to its own complex calculation.

Scope: This article compares PTA and PTE under current US patent law. All examples assume the 20-year-from-filing term framework for utility patents. PTE calculations involve FDA timing data that is beyond the scope of this guide.

What Is Patent Term Adjustment (PTA)?

PTA, codified at 35 U.S.C. § 154(b), adds days to a patent's term to compensate the applicant for delays caused by the USPTO during prosecution. The USPTO calculates PTA automatically and prints it on the face of the patent. PTA is composed of three categories:

A Delay (14/4/4/4 Guarantee)

The USPTO guarantees it will take certain actions within specified timeframes. If it fails, each day of delay is added as A Delay:

• Issue a first Office action within 14 months of the filing date.
• Respond to applicant replies within 4 months.
• Act on an allowed application within 4 months.
• Issue a patent within 4 months of paying the issue fee.

B Delay (3-Year Guarantee)

If the USPTO does not issue a patent within 3 years of the actual filing date (excluding certain periods such as RCE-related delays and applicant-requested delays), each additional day is counted as B Delay.

C Delay (Interference, Secrecy Orders, Appeal)

C Delay compensates for delays due to interference or derivation proceedings, secrecy orders, or successful appeals to the Patent Trial and Appeal Board (PTAB) or the Federal Circuit.

The PTA Formula

The total PTA = A + B + C − overlap between A and B − applicant delay. Applicant delay includes things like filing late responses, requesting extensions of time, or filing supplemental replies. The USPTO provides a detailed breakdown in each patent's PTA calculation (see MPEP § 2730).

What Is Patent Term Extension (PTE)?

PTE, codified at 35 U.S.C. § 156, extends a patent's term to compensate for time spent in regulatory review before the patented product could be commercially marketed. PTE applies to:

• Drug products (new drug applications under the FDCA)
• Medical devices (premarket approval applications)
• Biologics (approved through a Biologics License Application)
• Food and color additives (subject to premarket approval)

PTE must be applied for by the patent owner within 60 days after FDA approval. The extension is calculated based on the regulatory review period (time from IND filing to NDA approval, for drugs) and is subject to a maximum of 5 years. The total remaining patent term after the extension cannot exceed 14 years from the date of FDA approval.

Side-by-Side Comparison

Why Our Calculator Includes PTA but Not PTE

Our Patent Expiration Calculator automatically computes PTA because it is available from USPTO data for every patent and can be applied algorithmically. PTE, on the other hand, requires product-specific FDA approval data, applies to a small subset of patents, and involves regulatory timing calculations that go beyond standard patent data. We clearly note when a patent may have a PTE so users know to investigate further.

Worked Example: Patent with 206 Days of PTA

Brief Overview of PTE: Which Products Qualify

PTE is available for the first commercial marketing of a new product that required FDA premarket regulatory review. The key categories include:

• New drugs: Approved through a New Drug Application (NDA) under the Federal Food, Drug, and Cosmetic Act. These patents are listed in the FDA Orange Book.
• Medical devices: Approved through a Premarket Approval Application (PMA).
• Biologics: Approved through a Biologics License Application (BLA).
• Food and color additives: Subject to premarket approval.

Only one patent per product approval can receive a PTE, and the patent must claim either the product itself, a method of using the product, or a method of manufacturing the product.

Can a Patent Receive Both PTA and PTE?

Yes. A patent can receive both PTA (for USPTO prosecution delays) and PTE (for FDA regulatory delays). The two adjustments are independent: PTA is added first based on prosecution delays, and PTE extends the resulting term further based on the regulatory review period. However, the total effective extension under PTE is calculated based on the regulatory review period and is still subject to the 5-year cap and the 14-year post-approval limit.

In practice, a pharmaceutical patent might have, for example, 200 days of PTA and 3 years of PTE, resulting in a significantly extended patent life. This is particularly common for blockbuster drugs where the FDA approval process is lengthy.

Last reviewed: April 2026

Legal disclaimer: This article is for informational purposes only and does not constitute legal advice. Consult a registered patent attorney or agent for advice specific to your situation. patentreply.ai is not a law firm.