Section 575.308 - Approval criteria and written determination(a) An agency in its sole and exclusive discretion, subject only to OPM review and oversight, may approve a retention incentive for an individual employee or group or category of employees using the approval criteria in § 575.306 .(b) For each determination to pay a retention incentive under this subpart, an agency must document in writing- (1) The basis for determining that the unusually high or unique qualifications of the employee (or group of employees) or a special need of the agency for the employee's (or group of employees') services makes it essential to retain the employee(s);(2) The basis for determining that the employee (or a significant number of employees in a group) would be likely to leave the Federal service in the absence of a retention incentive; and(3) The basis for establishing the amount and timing of the approved retention incentive payment and the length of the required service period.