Patents have a standard term, but certain circumstances allow patent owners to extend that term beyond the normal expiration date. Two mechanisms accomplish this: patent term adjustment and patent term extension. Though the names sound similar, these provisions serve different purposes and address different delays.
Understanding these mechanisms helps patent owners maximize the value of their patents and recover time lost to administrative or regulatory delays beyond their control.
Typical Utility Patent Term
Utility patents expire 20 years from the earliest effective filing date. For most patents, this means 20 years from the filing date of the application that issued as the patent, or from the filing date of an earlier application to which the patent claims priority.
This term begins when the application is filed, not when the patent issues. Because prosecution often takes several years, the effective term of patent protection—the time between grant and expiration—is less than 20 years.
Patent Term Adjustment
Patent term adjustment compensates applicants for delays caused by the USPTO during prosecution. Congress enacted this provision in the American Inventors Protection Act of 1999, codified at 35 U.S.C. § 154(b).
The USPTO must examine applications within certain timeframes. When the USPTO fails to meet these deadlines, the patent receives additional term equal to the delay. Three categories of delays qualify for adjustment:
Category 1: when the USPTO fails to act within 14 months from filing, reply to an appeal within four months, act within four months after a decision from the Patent Trial and Appeal Board, or issue a patent within four months of the issue fee payment.
Category 2: occurs when the USPTO fails to issue a patent within three years of the filing date. This calculation excludes time consumed by continued examination requests, appeals, secrecy orders, and delays caused by the applicant.
Category 3: includes unusual delays in individual applications, such as extended failures to act or lapses in processing.
The USPTO calculates patent term adjustment and provides notice on the front page of the issued patent. Applicants may request reconsideration of the calculation within two months of grant.
Applicant-caused delays reduce the adjustment. If the applicant fails to respond to an Office action within three months, fails to proceed with reasonable promptness, or takes other specified actions, the USPTO subtracts that time from the adjustment.
Patent Term Extension
Patent term extension compensates patent owners for time lost during regulatory review. This mechanism applies to patents covering products that require premarket approval from agencies like the Food and Drug Administration or the Environmental Protection Agency.
The Drug Price Competition and Patent Term Restoration Act of 1984, known as the Hatch-Waxman Act, created this provision. The statute appears at 35 U.S.C. § 156.
Patent term extension applies to patents covering:
- Human drugs, including biological products
- Medical devices
- Food additives
- Color additives
- Animal drugs
- Veterinary biological products
The extension compensates the patent owner for time spent in regulatory review. The maximum extension is five years, though the total patent term from the date of regulatory approval cannot exceed 14 years.
The patent owner must apply for extension within 60 days of receiving regulatory approval. Only one patent per product may receive extension, and each patent may receive extension only once.
The extension applies only to claims covering the approved product or method of using or manufacturing the product. It does not extend the term for all claims in the patent.
Key Differences
Patent term adjustment and patent term extension serve different purposes and operate under different rules.
Patent term adjustment compensates for USPTO delays during prosecution. It applies to all utility patents and occurs without a separate application. The USPTO calculates the adjustment when the patent issues.
Patent term extension compensates for regulatory review delays. It applies only to patents covering products that need premarket approval. The patent owner must apply for extension after receiving regulatory approval. The extension applies only to claims covering the approved product.
A patent may receive both patent term adjustment and patent term extension, though limitations apply to prevent overlapping compensation for the same delays.
Strategic Considerations
Patent owners should monitor USPTO delays during prosecution and verify the patent term adjustment calculation. Errors in calculation occur, and the USPTO will reconsider if the patent owner requests review within the specified time.
For patents covering products requiring regulatory approval, the patent owner must file the extension application within 60 days of approval. Missing this deadline forfeits the extension. Patent owners developing regulated products should identify relevant patents and prepare extension applications before regulatory approval arrives.
Because only one patent per product may receive extension, patent owners with multiple patents covering a product must choose which patent to extend. This choice depends on factors including remaining patent term, claim scope, and competitive landscape.
Conclusion
Patent term adjustment and patent term extension restore patent term lost to delays beyond the patent owner’s control. Patent term adjustment addresses USPTO delays during prosecution and applies to all utility patents. Patent term extension addresses regulatory review delays and applies to patents covering products requiring premarket approval. Understanding these mechanisms helps patent owners secure the full value of their patents and maintain protection for the intended period.
Justin Miller is a solo patent attorney. In 2025 he started his own law firm, Distinct Patent Law, after nearly 15 years of practice. His firm is located in Saint Petersburg Florida. He serves clients in Tampa Bay, and because patent law is federal, can file patent applications for clients all over the United States.