A temporary, one year, simplified patent application, which allows the applicant to claim a date of filing and patent pending status. File a patent application.Typically, an applicant has 30 or 31 months from the priority date to enter the national phase in each treaty member country where protection is sought. The priority date determines whether another patent filing or publicly available document qualifies as prior art against one's patent application. U.S. design patent applications are NOT permitted to claim priority to an earlier filed U.S. provisional patent application. The filing date is the date when a patent application is first filed at a patent office. The priority date, sometimes called the "effective filing date", A priority claim is made to an earlierfiled patent application. For example, an Applicant can claim priority in a later-filed patent application. Priority date refers to the earliest filing date in a family of patent applications.