5 CFR §531.402

1. (a)Except as provided in paragraph (b) of this section, this subpart applies to employees who—
   1. (1)Are classified and paid under the General Schedule;
   2. (2)Occupy permanent positions; and
   3. (3)Are paid less than the maximum rate of their grade.
2. (b)This subpart does not apply to any employee who is appointed by the President, by and with the advice and consent of the Senate.