5 CFR §630.1405

1. (a)An agency must use the same minimum charge increments for administrative leave as it does for annual and sick leave under § 630.206.
2. (b)Employees may be granted administrative leave only for hours within the tour of duty established for purposes of charging annual and sick leave when absent. For full-time employees, that tour is the 40-hour basic workweek as defined in 5 CFR 610.102, the basic work requirement established for employees on a flexible or compressed work schedule as defined in 5 U.S.C. 6121(3), or an uncommon tour of duty under § 630.210.
3. (c)Agencies authorize, and may require, the use of administrative leave by an employee or a category of employees. Employees do not have an entitlement to receive administrative leave, nor do they have a right to refuse administrative leave when the agency requires its use.