; and (II) monitors properties to ensure affordability is preserved. (3) Disqualified single family property owner For purposes of this subsection— (A) In general The term disqualified single family property owner means, with respect to any taxable year, any taxpayer who owns (directly or indirectly) 50 or more single family residential rental properties. (B) Aggregation rules All persons treated as a single employer under subsection (a) or (b) of section 52, or subsection (m) or (o) of section 414, shall be treated as one taxpayer for purposes of this section. (C) Modifications (i) In general For purposes of applying subparagraph (B)— (I) section 52(a) shall be applied by substituting component members for members , and (II) for purposes of applying section 52(b), the term trade or business shall include any activity treated as a trade or business under paragraph (5) or (6) of section 469(c) (determined without regard to the phrase To the extent provided in regulations in such paragraph (6)). (ii) Component member For purposes of this paragraph, the term component member has the meaning given such term by section 1563(b), except that the determination shall be made without regard to section 1563(b)(2). (iii) No inference The modifications made by clause (i) shall not be construed to create any inference with respect to the proper application of section 52 with respect to any other provision of this title. (4) Single family residential rental property For purposes of this subsection— (A) In general The term single family residential rental property means— (i) any residential rental property (as defined in section 168(e)(2)(A)(i)) which contains 4 or fewer dwelling units (as defined in section 168(e)(2)(A)(ii)(I)), and (ii) improvements to real property directly related to such dwelling units located on the site of such dwelling units. For purposes of clause (i), each townhouse or rowhouse shall be treated as a separate building. (B) Exception for certain properties Such term shall not include any residential