Patent Priority Date: An Overview

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The “right of priority” is a legal term used to describe an applicant’s ability to submit a first application in one jurisdiction disclosing a specific invention before submitting one or more additional applications, which are treated as having been submitted on the same date as the initial application. As a result, the initially filed application is not regarded as prior art for the applications that follow. The first application submitted under these circumstances is also referred to as a priority application” and the date on which this is filed is referred to as a “priority date”.  

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Priority Date: An Overview   

The earliest filing date within a family of patent applications is referred to as the priority date. The priority date would be the filing date of the sole application when just one patent application is involved. The priority date will be the date of the earliest patent filing that first disclosed the invention if an applicant has submitted several related patent applications. The initial patent file sometimes referred to as the priority application, maybe a foreign application, a nonprovisional patent application, or a provisional patent application. 

Significance of Priority Date  

An application may only assert precedence as of the priority date, which is established by a priority date patent. It also specifies which resources are included in the patent’s prior art. Because it can significantly affect an invention’s ability to be patented, it is crucial to get the earliest priority date feasible. 

In general, a priority claim establishes the priority date of a patent application for examination purposes at the U.S. Patent and Trademark Office (USPTO). But why does that matter? Because throughout a patent application’s inspection, the priority date effectively dictates which references can and cannot be used as prior art. In other words, the priority date establishes a boundary for previous art that cannot be crossed. 

For instance, the following patent applications have been filed: 

  1. Provisional filed on June 10, 2016, disclosing features A and B of an invention; 
  2. Non-provisional filed on June 9, 2017, claiming priority to the 1/20/16 provisional and adding new feature C (i.e., disclosing A, B & C); and 
  3. CIP was filed on October 20, 2017, adding new feature D.

    In the above scenarios, the priority dates are: 
  • Features A & B: 6/10/2016 (filing date of provisional); 
  • Feature C: 6/9/2017 (filing date of non-provisional); and 
  • Feature D: 10/20/2017 (filing date of CIP). 

In essence, the first filing date for each feature is its priority date. It’s essential to submit the associated applications as soon as you can because new features are granted later priority dates depending on when they were initially disclosed in a patent filing. To limit the number of prior art references that can be referenced against claims stating your novel features, you should seek for the earliest priority date feasible. 

Types of Patent Priority Dates  

Your priority date will be one of the following options, according to your specific circumstances: 

  • The filing date of the provisional application, if it was your earliest-filed patent application for a certain invention; 
  • If your initial filing was a non-provisional application, the filing date of the non-provisional application would be used;  
  • If your first filing was an overseas or foreign application, the filing date of the non-US application would be used. 

How to Claim a Priority Date? 

The first step in establishing a priority date is to submit a patent application that details the invention’s creation and usage (i.e., enablement requirement). The inventor has asserted a priority date at the time the patent application is submitted. It’s like putting a stake in the ground to show that the invention belongs to the inventor, at least as of the filing date. 

The inventor may then submit more patent applications after that (i.e., continuation patent application, PCT application, national applications). These subsequent applications ought to trace their priority to the first patent application submitted. To do this, you must refer to the previously filed patent application and submit the subsequent applications while it is still pending. Because every situation is unique, you need to enlist the aid of a patent attorney to guide you through the procedure. 

Multiple Priorities 

One or more earlier applications may be cited as the priority source for subsequent applications. When claiming multiple priorities, the applicant may do so from either one jurisdiction or several other jurisdictions. In multiple priorities, two or more applications are related in such a way that it constitutes a single invention. Once these requirements have been met, the applicant may submit a multiple-priority application within 12 months of the earliest application filing date.  

Multiple priorities are subject to the fundamental priority rule, and an earlier invention must support the entire specification for which the application may be filed. The earliest filing date, or the date the matter was first disclosed, would be the priority date. 

The following situations would qualify as disclosures in a prior application

The basic application is the earliest application that was filed of the subject matter whether it was disclosed or claimed in the principal application. Whether it was made known in any materials the applicant for patent protection submitted alongside the application. 

A copy of the document must be submitted with the convention application for it to be accepted. Alternatively, it may be submitted within the time frame that may be established following the submission of that application. 

Patent Filing Date vs Priority Date  

The words filing date and priority date are sometimes used synonymously, but they are not the same. The date a patent application is initially submitted to a patent office is known as the filing date. The priority date, also known as the “effective filing date,” is the date used to determine whether an invention is original or obvious in comparison to the prior art. 

The application filing date may not match the priority date exactly. An application’s priority date may match the parent application’s if it claims priority to an earlier parent application. 

A patent application frequently asserts priority over a number of applications. A continuation application might, for instance, assert priority over a parent utility application that itself asserts priority over a US provisional application. The new application may then assert priority over the provisional application, which was the first application in the series to be filed. 

The filing date of a patent application is often the same as the priority date if it is an original, non-provisional patent application, not a continuation application, and was not previously filed in another nation. 

When a Patent Application May Claim Priority to an Earlier Application? 

A patent application may assert priority over a prior application in a number of circumstances. These consist of: 

  1. Continuation applications: A patent application may assert priority over a parent application that was filed first. When this happens, the priority dates of the new application and the parent application are typically equal. 
  2. Domestic applications based on foreign or international filings: A patent application may use the filing date of the application in the foreign country as its priority date if it is first submitted internationally or as an international (PCT) application, and then it is filed domestically (often within a year of the foreign or international filing). 
  3. Patent filings based on US provisional patent applications: In the US, an applicant may submit a provisional patent application and then, within a year, a complete application. The date of filing of the provisional application in this instance serves as the priority date for the full-length application. 

Priority Date: Maintained or Lost  

Because the USPTO operates according to the first-to-file principle, keeping the earliest priority date is preferred. When a patent family is involved, a priority date might be both kept and lost. 

Most frequently, failure to convert a provisional to a non-provisional within 12 months of the provisional filing date results in the loss of a priority date. Re-filing the provisional necessitates a later priority date, which increases the likelihood that further prior art will be used against the applicant. 

With the exception of cases when a PCT application is submitted to extend the time for US applications to be filed in each distinct foreign jurisdiction, international or foreign filings must be made within 12 months of the US priority date.

Important Deadlines with Regard to Priority

12 months: You must submit an application for the same invention in a different nation within a year of submitting your initial application if you want your application to be given priority in that nation. 

16 months: You have 16 months from the priority date, or the filing date of your first application, to request priority based on an earlier application. 

If this is a later date, you may also request priority within four months of the date on which you submitted your new application. 


A patent protects your invention as of the priority date. After then, you can disclose your invention. Given that the priority dates of the multiple priorities play a crucial part in the grant of a patent, claiming multiple priorities benefits the applicant significantly. It makes sure that disclosure in previous applications or innovations won’t interfere with the final invention’s ability to obtain a patent or with later registrations in other countries. This priority option, in turn, reimburses the inventor for the costs incurred during research and development, encouraging the development of new ideas. 

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