The annuity of a participant shall be equal to 2 percent of his or her average basic salary for the highest 3 consecutive years of service multiplied by the number of years, not exceeding 35, of service credit obtained in accordance with sections 4056 and 4057 of this title, except that the highest 3 years of service shall be used in computing the annuity of any participant who serves an assignment in a position, as described in
section 3942(b) of this title, to which the participant was appointed by the President and whose continuity of service in that position is interrupted prior to retirement by appointment or assignment to any other position determined by the Secretary of State to be of comparable importance. In determining the aggregate period of service upon which the annuity is to be based, the fractional part of a month, if any, shall not be counted. The annuity shall be reduced by 10 percent of any special contribution described in
section 4045(d) of this title which is due for service for which no contributions were made and which remains unpaid unless the participant elects to eliminate the service involved for purposes of annuity computation.