What is a Priority Date of a Patent of Addition?

This Article would not discuss as to what is a patent of addition, when does it expire etc., answers to which are clearly mentioned in the Indian Patents Act. Briefly to sum up, a Patent of addition can be filed at any time either before or after the grant of a main application for an improvement/modification on the main invention and expires with an expiry of the main patent (Sections 54, 55 of the Patents Act). Further Section 56 of the Patents Act clarifies that a main application/patent cannot be cited to establish lack of inventive step in the patent of addition but can be cited to establish novelty in the patent of addition.

Coming to a moot point of our discussion that is what the priority date of patent of addition is. Well, this is a question for which we always get answers stating that the original filing date of the main application is a priority date of the patent of addition. Not only our interview candidates, peers, colleagues, but, yes you will read it right, even our respected Indian patent office controllers had told us the same answer!

That is when we protested in order to save one of our client’s rights. The identity of our client as well as the Controller we have spoken to has not been disclosed herein.

So here it goes, our client had filed a patent application (hereinafter referred to as “main application”) on 17th October 2008 and an application for a patent of addition on 22nd June 2010 (containing new matter and new claims) during the pendency of the main application. According to an Indian Patent office website regarding the status of this Application, we were very surprised to learn that the said patent of addition application has been “Deemed to be withdrawn u/s 11B(4)” for non-request of examination.

We had written our grievance letter to the Patent Office on behalf of our client emphasising mainly on the following points as discussed herein below.

Each Patent of Addition is clearly an independent patent in view of Sections 54 and 55 of theIndian Patent Act, and therefore

  • rendered a new Application Number,
  • requires a separate request for examination to be filed,
  • is published after 18 months, and
  • undergoes separate examination.

In view of the same, the deadline for request for examination of a Patent of Addition has to be 48 months from the date of filing of the Patent of Addition, which in the present case should be 22’nd June 2014.

We requested the Patent Office to give a reason for which the application has been “Deemed to be withdrawn u/s 11B(4)” for non-request of examination. We further contended that it is completely logical to say that the priority date of a patent of addition is the date of filing of the application for patent of addition. Else, what would be the deadline for filing a request for examination in case the application for a patent of was filed after 48 months from the main invention? For example, what should be a deadline of filing a request for examination for a patent of addition application where the main application was filed on 01st January 2001 which was granted on 01st January 2005 and the patent of addition application was filed on 01st January 2006? How can a 48-month deadline of filing RFE from priority date of main application be complied in this case?

Further logic can be easily drawn from the right to file a PCT application for a patent of application. Had it been so that a patent of addition has a priority date of the original application, would an applicant for a patent of addition application, in that case, be not entitled to file a PCT application in case the patent of addition application is filed after 12 months from the date of filing of the main application. For example, if a main application was filed on 01st January 2005 and a patent of addition application was filed on 01st January 2007 and if, as the patent office says, a priority date of the patent of addition application is taken as the original filing date of main application, does that mean that an applicant cannot ever file a PCT application for his patent of addition application.

Our discussions with the respected Controllers in this matter made us give a rational that “it is obvious” that a priority date of patent of addition is the main application filing date as both are expiring on the same date. We were also justified that Patent of Addition is rendered as a “further application” in context of the Indian Patent Act, which made us feel the wide gap that non-mention of the actual deadline in the Patent Act actually made. It was only after we had explained to him giving all logical reasons and explanations (as discussed above) as to why the priority of the patent of addition (containing new matter and claims) cannot be the original main application filing date, was when the concerned Controllers got the point and agreed and accepted that our client’s application has been deemed withdrawn incorrectly, the status of which has now been rectified to state “Examination Request Not Filed”!!

We are fortunate that we were not made to contest this matter at the IPAB, which would have been such an unnecessary investment of time and energy, for an issue which is amply clear and logical. This article is merely being written to share a commonly misunderstood concept relating to patent of addition and provide clarity to all our inventors and patent agents of their rights of priority in case of patent of addition.

Happy Patenting!

About the Author: Ms. Meenakshi Khurana, Patent Attorney at Khurana & Khurana and can be reached at: Meenakshi@khuranaandkhurana.com

Follow us on Twitter: @KnKIPLaw .

4 thoughts on “What is a Priority Date of a Patent of Addition?”

  1. Megha Panpalia says:

    very informative article…thanks for clarifying as this would really help in understanding the concept of patent of addition clearly which would surely help me out in upcoming patent agent examination….thanks again!!!

  2. Can anybody let me know the timeline/deadlne for filing a Request for Examination (RFE) for a ”patent of addition”? For example, if the parent application is filed in March 2013 and a subsequent ‘patent of addition’ is filed on March 2014, can I consider that the deadline for filing RFE for ‘patent of addition’ is March 2018 (i.e. 48-month from the filing date?). Please help me with this since thhe Patents Act is silent in this regard.

    1. Vikas your understanding is correct. Priority of a Patent of Addition is the date on which the Patent of Addition application was filed, and therefore the 48 months would start from that filing. Please let us know in case of any clarification.


  3. Everybody writes about laws relating to patent of addition. These laws are mentioned (tersely) in the IPO. It will be helpfull if we can have an example template of patent of addition atleast as a template. Applicants need to know how does the abstract, background of invention, summary, description and most importantly claims should look like.
    It is difficult to understand how to write claims because we can NOT mention previous patent application number in the claims. how one can mention improvement or additional feature.

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