5 CFR § 831.302 - Unused sick leave.
(a) For annuity computation purposes, the service of an employee who retires on immediate annuity or dies leaving a survivor entitled to annuity is increased by the days of unused sick leave to his credit under a formal leave system.
(b) An immediate annuity is one which begins to accrue not later than 1 month after the employee is separated.
(c) A formal leave system is one which is provided by law or regulation or operates under written rules specifying a group or class of employees to which it applies and the rate at which sick leave is earned.
(d) In general, 8 hours of unused sick leave increases total services by 1 day. In cases where more or less than 8 hours of sick leave would be charged for a day's absence, total service is increased by the number of days in the period between the date of separation and the date that the unused sick leave would have expired had the employee used it (except that holidays falling within the period are treated as work days, and no additional leave credit is earned for that period).
(e) If an employee's tour of duty changes from part time to full time or full time to part time within 180 days before retirement, the credit for unused sick leave is computed as though no change had occurred.