D.C. Mun. Regs. tit. 6, r. 6-B1234
If a temporary appointment is for less than ninety (90) days, the employee shall not be entitled to earn annual leave.
If a temporary appointment for less than ninety (90) days is extended for an additional ninety (90) days or longer without a break in service, or if there are successive temporary appointments without a break in service that aggregate ninety (90) days or longer, then the employee shall receive retroactive credit for leave earned from the date of appointment, and shall earn leave thereafter.
Retroactive annual leave credited, or annual leave earned thereafter as specified in section 1234.2 of this section, shall not be substituted retroactively for either compensatory time or leave without pay taken during the period described in section 1234.1 of this section.
D.C. Mun. Regs. tit. 6, r. 6-B1234