D.C. Mun. Regs. tit. 6, r. 6-B1235
Annual leave may be used by an employee for any reason, but is intended primarily to be used for the following two (2) general purposes:
Annual leave shall be requested and approved no later than twenty- four (24) hours prior to the day on which the annual leave is to be used. Employees are required to obtain approval for the use of annual leave by whichever method is formally established within his or her agency. Annual leave requested and approved at least 24 hours prior to the leave period shall constitute "scheduled annual leave;" leave approved with less than 24 hours' notice is deemed "unscheduled annual leave" for recordkeeping purposes.
The annual leave provided by this chapter, including annual leave that has been advanced as provided in section 1237 of this chapter, may be granted at any time during the leave year in accordance with these regulations.
An employee is entitled to his or her annual leave, and the taking of annual leave for the purposes set forth in subsection 1235.1 of this section should be encouraged, subject to scheduling approval by the agency head.
An approved absence that would otherwise be properly chargeable to sick leave may be charged to annual leave, compensatory time, or leave without pay, if requested in advance by the employee and approved by the agency head.
D.C. Mun. Regs. tit. 6, r. 6-B1235