A priority date patent establishes the priority date as the earliest date an application may claim precedence. It also defines what materials are prior art to the patent. This is why it's important to obtain the earliest possible priority date as it can play a key role in the patentability of particular inventions.

In a situation with only one patent application, the priority date is the same as the filing date for the single application. When there are multiple related patent applications, the application's priority date is the filing date of the earliest patent that initially disclosed the invention.

It's known as the priority application, and the earliest patent filing can be one of three types:

This term can also reference the earliest filing date for a specific aspect of your invention. This means it's conceivable to have various priority dates if the applicant added new features in related patent applications.

What is a Patent Filing Date?

The patent filing date is when the United States Patent Office recognizes the application for your patent was filed. It's a key date as it establishes who has priority, or which application should get the patent first. If you have two parties who've filed patent applications at the same time on a similar invention, the one who filed first has priority. There are situations where the filing date on your patent application is different than whatever date you filed the application, which results in the distinction between the effective filing date and the actual filing date.

What is the Actual Filing Date?

When you hear the term actual filing date, this is the date that someone physically submitted, or filed, the application with the United States Patent Office. All filing dates are very significant in patent law because these dates can establish who the first inventor was and who should be the first to be entitled to a patent. Filing dates can also determine how long the patents rights are good for. If your application for a non-provisional patent is approved, you're given patent rights for 20 years, which start running on your actual filing date.

What is the Effective Filing Date?

An application can “inherit” another application's previous filing date to determine the effective filing date. If you file for a provisional patent application, it means you're preserving the filing date before you opt to start the full and more expensive process of a non-provisional application.

For example, you file the provisional patent application on February 1, 2019, and then file the non-provisional one December 1, 2019. The actual filing date would be December 1, 2019, but the effective filing date would be February 1, 2019. In the event someone files an application between these dates, the provisional application would still take priority over the other person's application and be the first one entitled to a patent. This is what it means when your application inherits the provisional application's filing date. As far as the Patent Office is concerned, your application is ahead of the other person's application even though you didn't file the non-provisional patent application earlier than they did. The provisional application essentially saves the date to be utilized by the non-provisional application later on.

Different Types of Priority Dates

If your first application was a provisional patent application, then this is your priority date. If your first application was a non-provisional application, then that is your priority date. In the event you filed an international or foreign-filed application first, then that filing date is your priority date.

Priority dates are important to help establish whether another filing or any publicly available document qualifies as prior art against your patent application. In general, any patent applications and publicly available documents filed prior to your priority date are considered prior art.

You can maintain your priority date by filing as early as possible as the United States Patent Trademark Office operates under the rule of who is first to file. Since the priority date can be retained, it also means it can be lost, especially when a patent family is involved. A common way a priority date is forfeited is when the applicant fails to convert a provisional application to a non-provisional application within a year of the provisional application date. If you refile the provisional application, it opens the door to more prior art that may be used against your application.

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