24 CFR § 990.150 - Limited vacancies.
(a) Operating subsidy for a limited number of vacancies. HUD will pay operating subsidy for a limited number of vacant units under an ACC. The limited number of vacant units must be equal to or less than 3 percent of the unit months on a project-by-project basis based on the definition of a project under § 990.265 (provided that the number of eligible unit months does not exceed 100 percent of the unit months for a project).
(b) Exception for PHAs with 100 or fewer units. Notwithstanding paragraph (a) of this section, a PHA with 100 or fewer units will be paid operating subsidy for up to five vacant units not to exceed 100 percent of the unit months under an ACC. For example, a PHA with an inventory of 100 units and four vacancies during its fiscal year will be eligible for operating subsidy for all 100 units. A PHA with an inventory of 50 units with seven vacancies during its fiscal year will be eligible for operating subsidy for 48 units.