regulations prescribed under section 52(b). In the case of a corporation which is a member of an affiliated group of corporations filing a consolidated return, such corporation shall be treated as selling fuel to an unrelated person if such fuel is sold to such a person by another member of such group. (4) Pass-thru in the case of estates and trusts Under regulations prescribed by the Secretary, rules similar to the rules of subsection (d) of section 52 shall apply. (5) Allocation of credit to patrons of agricultural cooperative (A) Election to allocate (i) In general In the case of an eligible cooperative organization, any portion of the credit determined under subsection (a) for the taxable year may, at the election of the organization, be apportioned among patrons of the organization on the basis of the amount of business done by the patrons during the taxable year. (ii) Form and effect of election An election under clause (i) for any taxable year shall be made on a timely filed return for such year. Such election, once made, shall be irrevocable for such taxable year. Such election shall not take effect unless the organization designates the apportionment as such in a written notice mailed to its patrons during the payment period described in section 1382(d). (B) Treatment of organizations and patrons The amount of the credit apportioned to any patrons under subparagraph (A)— (i) shall not be included in the amount determined under subsection (a) with respect to the organization for the taxable year, and (ii) shall be included in the amount determined under subsection (a) for the first taxable year of each patron ending on or after the last day of the payment period (as defined in section 1382(d)) for the taxable year of the organization or, if earlier, for the taxable year of each patron ending on or after the date on which the patron receives notice from the cooperative of the apportionment. (C) Special rules for decrease in credits for taxable year If the amount of the credit of a cooperative organization