Patent maintenance fees are also referred to as patent renewal fees or patent annuity fees. These fees
are paid to the USPTO to maintain a granted patent. Patent maintenance fees are required for utility
patents in the United States during the course of a 20-year period. This 20- year period starts at the time
you file the patent or during the priority date. The fees are paid in three separate payments. After
issuance of a utility patent, maintenance fees are due 3.5 years, 7.5 years and 11.5 years after the date
of patent grant. There are no maintenance fees for design patents and plant patents.