; and (II) difficulty in the recruitment and retention of CBP employees in the area; and (iii) in the absence of a retention bonus, the CBP employee would be likely to leave— (I) the Federal service; or (II) for a different position in the Federal service, including a position in another agency or component of the Department of Homeland Security; and (B) the individual enters into a written service agreement with the Secretary— (i) under which the individual is required to complete a period of employment as a CBP employee of not less than 2 years; and (ii) that includes— (I) the commencement and termination dates of the required service period (or provisions for the determination thereof); (II) the amount of the bonus; and (III) other terms and conditions under which the bonus is payable, subject to the requirements of this subsection, including— (aa) the conditions under which the agreement may be terminated before the agreed-upon service period has been completed; and (bb) the effect of a termination described in item (aa). (4) Rules for bonuses (A) Maximum bonus A bonus paid to an employee under— (i) paragraph (2) may not exceed 100 percent of the annual rate of basic pay of the employee as of the commencement date of the applicable service period; and (ii) paragraph (3) may not exceed 50 percent of the annual rate of basic pay of the employee as of the commencement date of the applicable service period. (B) Relation to basic pay A bonus paid to an employee under paragraph (2) or (3) shall not be considered part of the basic pay of the employee for any purpose. (5) OPM oversight The Director shall, to the extent practicable— (A) set aside a determination of the Secretary under this subsection if the Director finds substantial evidence that the Secretary abused the discretion of the Secretary in making the determination