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  • Rahul Vijh

Is your patent expiring? Here's how to calculate patent expiration dates!

Every government has a duty to encourage innovations that are unique and useful to the society. Building a mechanism that ensures product credibility is one of the reasons why we need patent law. The patent law, however, requires that a patent application explain the invention to someone who is not already familiar with the invention. Here is a list of best patent drafting practices, to be kept in mind. Patents give an inventor the right to exclude others from making, selling or using the invention and in lieu, the inventor discloses the invention to the world – so that the world advances its collective knowledge. Yet – the exclusivity granted to the inventor may also cause hindrance to the society and imbalance in economies – which is why patent rights come with an expiration date. Once a patent expires, the invention falls into “public domain” which means it can be practiced by anyone without owing royalties to the patent owner. Knowing when a patent will expire sounds like it would be as easy as just opening the patent and looking at the bibliographic data on the patent. In practice however, due to how intellectual property law has continued to evolve around the world, calculating patent expiration dates is a murkier business and often requires legal analysis. In this article we take a look at how patent expiration dates are typically calculated in the major IP centers of the world:


In the United States the expiry date for utility patents is 20 years from the filing date, or from the date of the earliest related non-provisional application. This resulted from a change in the patent law in June 1995, when prior to this time, the expiry date was 17 years from the issue date or 20 years from the filing date, whichever came later. So a patent that has a filing date of 20 July 2000 but has a continuation in part filed on 23 November 1997, which also has a continuation in part filed on 16 September 1996, will have the expiry date on 15 September 2016 and not 19 July 2020, as the earliest filing date is taken into consideration. For design patents the term is shorter – As of May 13, 2015 the term is 15 years from the date of issuance. This may seem like the most straight forward process, but in cases where there are multiple divisions or continuations-in-part, especially which have spanned for more than 20 years, it becomes particularly deceptive.

Let’s take an example patent application, understanding how it advances from the first application date to its expiration.

  • A provisional application X is filed on June 13, 1998

  • A non-provisional patent application P1 is filed on June 12, 1999.

  • Expiry date of P1 - June 11, 2019

  • A continuation application P2 is filed on May 10, 2000, adding new claims.

  • Expiry date of P2 - June 11, 2019

  • A divisional is filed on September 2, 2001, segregating P2 into 2 parts (say P2A and P2B).

  • Expiry date of P2A and P2B - June 11, 2019

  • A continuation-in-parts P3 is filed on December 3, 2002 to P2A. If this addition to P2A is non-obvious and unrelated to the parent application P2A, the expiration date of claims covering the additions would require to be re-adjusted according to the recent filing date.

  • Expiry date of P3 “new subject matter” claims - December 2, 2022

  • However, if the change was insignificant or just an extension of the original application, the expiry date would remain unchanged.

  • Expiry date of P3 “inherited subject matter” claims - June 11, 2019

It is important to note that for a continuation-in-parts (CIP) application, claims to subject matter also disclosed in the parent application are entitled to the parent’s priority date, while claims to the additional subject matter are only entitled to the filing date of the CIP application.

A patent's term is shortened if it duplicates the claims of another patent which expires sooner. This process is called terminal disclaimer. If the applicant is required to file, and does file, a terminal disclaimer in the later filed patent, then the later filed patent will expire at the same time as the formerly filed patent, the extra term having been disclaimed.

There are instances when the United States Patent and Trademark Office (USPTO) fails to examine a patent application in time. In such cases, the patent term may be extended. However, if there are extensions or delays found on the applicant’s part, it can cause the extension to be reduced or eliminated.

Further, if a granted patent is reissued (for example, the inventor wishes to correct errors in a granted patent) or reexamined, the reissued patent expires on the day the original patent would have ordinarily expired.


The European Patent Convention requires all jurisdictions to give a European patent a term of 20 years from the actual date of filing the application, or the date of filing an international application under the PCT designating the EPO. The actual date of filing doesn’t necessarily have to be the earliest priority date; it can be up to a year after it. Although the term of a granted European patent may be extended under national law if it provides term extension to compensate for pre-marketing regulatory approval. For EEA member states this is by means of a supplementary protection certificate.


There are 4 different routes to obtain a patent in Germany:

  1. Direct filing of a national patent application with the GPTO (German Patent and Trademark Office).

  2. Filing a European patent application.

  3. Filing an international application under the Patent Cooperation Treaty.

  4. EURO-PCT route.

A German patent has a term of 20 years, whereas for a utility model, the maximum protection period is 10 years. After the priority date is filed, the window for filing a patent application in Germany is 12 months. The certified German translation for an application filed in French or English, must be provided within 12 months from filing the application, or 15 months from the earliest priority date.


The French law determines 2 different types of protection for technical invention – One is for the patent of invention, the other one being utility certificate. A patent is granted for a duration of 20 years with a search report, whereas in the case of a utility certificate, its 6 years without a search report. In order to obtain a patent of invention, the inventor has to first request an establishment of the research paper, and pay the required fee at the filing of the application. The search report is issued together with a written opinion from the Examiner relating to the validity of the claims. To keep the patent protection in force, the applicant has to pay a renewal fees at the end of the anniversary month of the filing.


In the Great Britain, the expiry date for a patent is the day preceding the 20th anniversary of the filing date. Thus a patent filed on November 21, 1995, shall have an expiry date of November 20, 2015. Although the term of a patent is not extendable beyond the 20 year period, exceptions are observed for a medical product or a plant protection product, which may be protected for an additional period of 5 years from the expiry date of a patent, at the end of the 20 year term. In order to implement the grant, a supplementary protection certificate is required. After the end of the fourth year from the date of filing, renewal fees must be paid for each succeeding year. In case of any overdue, the patent shall cease to have effect at the end of such day, in the final month of that period, as may be prescribed.


In Denmark, the term for filing patent application under Paris convention is 12 months from the date of priority. Priority can be claimed within three months of filing and a certified copy of the priority document must be filed within 16 months of the priority date. The patent is provided protection for 20 years from submission date, however in the case of pharmaceutical patents, the maximum term is 15 years (since 02.01.1993). Under the European Patent Convention, a European patent application is granted preliminary protection in Denmark from the date of publication. However, this only comes into effect after if a translation of the claims is provided and filed in the Danish Patent Office within 20 months of the International filing date.


The patent law of the People’s Republic of China was enforced on 12 March 1984, following its amendments on 4 September 1992 and 25 August 2002. Patents in China are granted by the State Intellectual Property Office (SIPO). Invention patents are substantively examined, while utility model patents are subject only to a formal examination. Invention patents are enforceable for up to 20 years from the application date whereas for utility models and designs, its 10 years from the application date.


The Japanese patent law follows the first-to-file (FTF) principle and is given force by the patent act of Japan. First to file (FTF) and first to invent (FTI) are legal concepts that define who has the right to the grant of a patent for an invention. The Japanese patent law, allying to other countries, too had its series of amendments. Prior to 1 July 1995, the term of a Japanese patent was 15 years from the date of examined publication but not in excess of 20 years from the filing date". On 1 July 1995, the law for the patent term was changed to 20 years from the filing date (which also applied to patents already in force on 1 July 1995). For utility patents before 1994 the term for the patent was 10 years from the date of examined publication, not exceeding 15 years from the filing date. In 1994, it was reduced to six years from the application date. However on 1 April 2005, the term got restored back to 10 years from the date of application.


For South Korea, the Korean intellectual property office is responsible for all matters related to patents, utility models and industrial designs. Utility patents which are rather referred to as innovative or minor patents, are valid for ten years, whereas invention patents which are regarded more advanced in terms of research and the work put on it, are given a protection for 20 years. Industrial designs which come under the design act, the law confers protection for a maximum of 15 years.


The legal system regulating the granting of patents for inventions within Canada, and their enforcement, is governed by the Canadian patent law. For patent applications filed prior to October 1, 1989, the patent expiration date is 17 years from the date of issuing. However, for patents that did not expire before July 12, 2001, the term is 17 years from the issued date or 20 years from the filing date, whichever comes later. The patent applications filed on or after October 1, 1989, have an expiration date 20 years after the date of filing of the application.


Much like the rest of the world, when it comes to patent law, Australia too operates on a first-to-file system. The patent act 1990 (Cth), provided that the term for a standard patent is 20 years. An innovative patent, which has a lower threshold of effectiveness, is granted a maximum term of 8 years, although it has a faster approval process and lower fees.


In India, the term of the patent is 20 years from the date of filing, regardless of whether it is filed with provisional or complete specification. The Indian patent law which exists today is a development of 3 important amendments. The patents (amendment) act, 1999 brought two significant changes:

The first being the Exclusive Markets rights, which means the right to sell or distribute the article or substance covered in a patent or patent application in the country.

The second was the mailbox facility, under which, applications for pharmaceutical and agro-chemical product patents were accepted during the ten-year transition period, and a filing date was assigned to each. This was a substantial step as at that time as pharmaceuticals did not qualify for a product patent; they were covered under the category of process patents.

The 20-year term was introduced by the Patents (Amendment) Act 2002, which wasn’t brought into effect until May 20, 2003. Prior to this date, the term of a product patent was 14 years from the date of filing, whereas for a process patent it was 5 years from the date of sealing or 7 years from the date of filing, whichever was earlier.

The third amendment in 2005 was the most significant one, as it brought the act in complete compliance with the TRIPS agreement and commenced India as a product patents regime, where earlier process patents ruled the day, especially in India's pharmaceutical industry.

Disclaimer: This article and its substance is not a legal opinion and should not be considered legal advice. Copperpod IP encourages readers to seek legal opinion from a practicing patent attorney (or ask us to recommend one!) for calculating patent expiration dates on a case-by-case basis.

Copperpod provides portfolio analysis services that help clients to make strategic decisions such as In-licensing/Out-Licensing of patents, new R&D investments, or pruning out less critical patents. Our qualified and dedicated team of patent engineers provides strength parameters for each patent in a portfolio based on their technical quality, enforceability, offensive/defensive strengths & business value.

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