5 CFR §630.208

1. (a)When the number of hours in a nonpay status in a full-time employee's leave year equals the number of basepay hours in a pay period, the agency shall reduce his credits for leave by an amount equal to the amount of leave the employee earns during the pay period. When the employee's number of hours of nonpay status does not require a reduction of leave credits, the agency shall drop those hours at the end of the employee's leave year. For the purpose of determining the reduction of leave credits under this paragraph when an employee has one or more breaks in service during a leave year, the agency shall include all hours in a nonpay status (other than nonpay status during a fractional pay period when no leave accrues) for each period of service during the leave year in which annual leave accrued.
2. (b)An employee who is in a nonpay status for his entire leave year does not earn leave.
3. (c)When a reduction in leave credits results in a debit to an employee's annual leave account at the end of a leave year, the agency shall:
   1. (1)Carry the debit forward as a charge against the annual leave to be earned by the employee in the next leave year; or
   2. (2)Require the employee to refund the amount paid him for the period covering the excess leave that resulted in the debit.
4. (d)A period covered by an employee's refund for unearned advanced leave is deemed not a nonpay status under this section.