5 CFR §534.504

1. (a)A rate of basic pay under this subpart must be—
   1. (1)Not less than 120 percent of the minimum rate of basic pay payable for GS-15 of the General Schedule, and
   2. (2)Not greater than—
      1. (i)The rate of basic pay payable for level III of the Executive Schedule (EX-III), or
      2. (ii)In the case of an SL or ST employee who is covered by a certified performance appraisal system or whose established rate of basic pay is preserved under § 534.509, the rate of basic pay payable for level II of the Executive Schedule (EX-II).
2. (b)An agency may not set or adjust the rate of basic pay for an SL or ST employee higher than the maximum in—
   1. (1)Paragraph (a)(2)(i) of this section (i.e., EX-III) when the SL or ST employee is covered by a performance appraisal system that is not certified or when the SL or ST employee is not subject to a performance appraisal system, except as provided in § 534.509; or
   2. (2)Paragraph (a)(2)(ii) of this section (i.e., EX-II) when the SL or ST employee is covered by a certified performance appraisal system.