such unit is an eligible unit under this section). (C) 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 (A) In general Family income shall be determined in the same manner as under section 8 of the United States Housing Act of 1937. (B) Time for determining income (i) In general Except as provided in this subparagraph, family income shall be determined at least annually on the basis of income for the preceding calendar year. (ii) Families on fixed income If at least 90 percent of the family income of the residents of a unit at the time of any determination under clause (i) is derived from payments under title II or XVI of the Social Security Act (or any similar fixed income amounts specified by the Secretary), the taxpayer may elect to treat such payments (or amounts) as the family income of such residents for the year of the determination and the 2 succeeding years, except that the taxpayer shall, in such manner as the Secretary may prescribe, adjust such amount for increases in the cost of living. (iii) Initial income The Secretary may allow a State to provide that the family income of residents at the time such residents first rent a unit in a qualified building may be determined on the basis of current or anticipated income. (iv) Special rules where family income is reduced If residents of a unit establish (in such manner as the rental reduction credit agency provides) that their family income has been reduced by at least 10 percent below such income for the determination year— (I) such residents may elect, at such time and in such manner as such agency may prescribe, to have their family income redetermined, and (II) clause (ii) shall not apply to any of the 2 succeeding years described in such clause which are specified in the election. (f) State rental