You can file a provisional patent application with a description and drawings to secure a priority date. Filed application for patent filed in the United States may claim the benefit of, or priority to, a prior application filed in the United States.The priority date determines whether another patent filing or publicly available document qualifies as prior art against one's patent application. Different claims in one application can have different earliest priority dates. What is a patent priority date? Priority date refers to the earliest filing date in a family of patent applications. If the claimed subjectmatter is disclosed in both priority applications, then the claim has the earliest date as effective date, i.e. P1.