with respect to the building. (B) State option A rental reduction credit agency may provide a credit period for any qualified building which is less than 15 years. (3) Eligible senior unit The term eligible senior unit means, with respect to any qualified building, a unit— (A) which is occupied by an eligible tenant, (B) the rent of which for does not exceed the family rental payment requirement determined under subsection (b)(3), and (C) which is certified to the rental reduction credit agency as an eligible senior unit for purposes of this section and the qualified rental reduction agreement. (4) Eligible tenant (A) In general The term eligible tenant means any individual if— (i) the individual's family income does not exceed the greater of— (I) 30 percent of the area median gross income (as determined under section 42(g)(1)), or (II) the applicable poverty line for a family of the size involved, and (ii) at least 1 of the occupants of the unit in which the individual will reside has attained the age of 55 as of the beginning of the lease. (B) Applicable poverty line The term applicable poverty line means the most recently published poverty line (within the meaning of section 2110(c)(5) of the Social Security Act ( 42 U.S.C. 1397jj(c)(5) )) as of the time of the determination as to whether an individual is an eligible tenant. (5) Family income Income of a family shall be determined by the taxpayer annually using the method set forth in the State rental reduction allocation plan. (e) State rental reduction allocation plan (1) Adoption of plan required For purposes of this section— (A) each State shall, before the allocation of its State rental reduction credit ceiling, establish and have in effect a State rental reduction allocation plan meeting the requirements of this subsection, and (B) notwithstanding any other provision of this section, the rental reduction credit amount allocated to any building shall be zero unless such amount was allocated pursuant to a State rental reduction allocation plan meeting