Special Pay Rates
According to the Office of Personnel Management (OPM) employees who are covered by a special rate schedule are entitled to the applicable special rate within that schedule unless they are entitled to a higher rate of basic pay under other authority (e.g., a higher locality rate or a retained rate).
In some cases, special rate schedules cover multiple locations where different locality rates apply. In some locations, the locality rate may be higher, while in other locations the special rate is higher. A special rate in a schedule is offered if it is higher in at least one location covered by the special rate schedule; however, that special rate is not applicable to an employee if he or she is stationed in a location where a higher locality rate applies.
For some special rate schedules, special rates may apply only at certain steps of a grade, since any applicable locality rate exceeds the special rate at other steps. This occurs in the case of special rate schedules for which the special rate supplement is a fixed dollar amount.