; and (2) by adding at the end the following: (m) (1) An employee may not be allowed credit under this section for any day of service spent principally on official time, as described under subsection (b), that is in excess of 365 days in the aggregate. (2) For purposes of this subsection, an employee spends a day principally on official time if at least 80 percent of the time such employee would otherwise be in a duty status during such day is spent on official time granted under section 7131. (3) Notwithstanding paragraph (1), any service described under paragraph (1) for which an employee is not allowed credit under this subsection shall be considered service for purposes of calculating the average pay of the employee under section 8401(3). . (c) Applicability The amendments made by this section shall apply to any applicable annuity calculated on or after October 1, 2017.