The patent year is calculated from the filing date and has nothing to do with the priority date or grant date, nor is it necessarily related to the natural year. For example, the filing date of a patent application is June 1, 1999, the first year of the patent application is from June 1, 1999 to May 31, 2000, and the second year is from June 1, 2000 to May 31, 2001, and so on.