37 CFR § 42.102 - Time for filing.
(a) A petition for inter partes review of a patent must be filed after the later of the following dates, where applicable:
(1) If the patent is a patent described in section 3(n)(1) of the Leahy-Smith America Invents Act, the date that is nine months after the date of the grant of the patent;
(2) If the patent is a patent that is not described in section 3(n)(1) of the Leahy-Smith American Invents Act, the date of the grant of the patent; or
(3) If a post-grant review is instituted as set forth in subpart C of this part, the date of the termination of such post-grant review.