D.C. Code tit. 42 § 42-3509.10

(a) A housing provider who reduces the number of units in a housing accommodation containing more than 3 and fewer than 11 units, each with a separate certificate of occupancy, including vacant buildings, shall pay the Mayor a fee of 5% of the appraised value of the most valuable unit in the building multiplied by the multiplier calculated pursuant to subsection (b) of this section.

(b) (1) To calculate the multiplier, the Mayor shall subtract the number of remaining units from the number of existing units, and then, if the housing provider so elects, subtract the number of remaining units that are exempted units.

(2) For the purposes of this subsection, the term "exempted unit" means a unit that:

(A) Is rented to a low-income household;

(B) Is rented to a tenant who, as determined by the Mayor:

(i) Has maintained a rental unit in the building complex as the principal place of residence for at least one year prior to the housing provider's reduction of the number of units;

(ii) Is a domiciliary of the District; and

(iii) Is entitled to the possession, occupancy, or benefits of the rental unit;

(C) Is rented to a person who is an elderly tenant or a tenant with a disability, as determined by the Mayor under § 42-3502.24(d) , that does not have a total annual household income, as determined by the Mayor, greater than 100% of the area median income, as that term is defined in § 42-2801(1) ; or

(D) Gains at least one additional bedroom in the process of the reduction of units.

(3) To qualify for an exemption under paragraph (1) of this subsection, a housing provider shall, for each exempted unit:

(A) Set the rent at no higher than:

(i) If seeking an exemption pursuant to paragraph (2)(A), (B), or (C) of this subsection, the rent level before the reduction in units or 30% of the tenant's income, whichever is lower; or

(ii) If seeking an exemption pursuant to paragraph (2)(D) of this subsection, an amount, determined by the Mayor through rulemaking, that is affordable to a household whose income does not exceed 100% of the area median income, as that term is defined in § 42-2801(1) ;

(B) Increase the rent by no more, and no more often, than the increases allowed under § 42-3502.08 for the duration of the tenant's tenancy or 5 years, whichever is longer; and

(C) Otherwise maintain the same lease terms as before the reduction in the number of units.

(4) The number calculated under paragraph (2) of this subsection shall not be less than zero.

(c) This section shall not apply to a building that the Mayor has determined to be a blighted vacant building, as that term is defined in § 42-3131.05(1) .

(d) The Mayor shall deposit into the Housing Production Trust Fund, created pursuant to § 42-2802 , all fees paid pursuant to this section as of April 16, 2020.

(e) For the purposes of this section, "low-income" means annual household income, as determined by the Mayor, no greater than 80% of the area median income, as defined in § 42-2801(1) .

(f) The Mayor, pursuant to subchapter I of Chapter 5 of Title 2 , may issue rules to implement the provisions of this section.