or (C) in the case of an eligible employer other than a partnership or S corporation, the amount of the business credit carryforward under section 39 carried from the taxable year (determined before the application of this subsection to the taxable year). (3) Election (A) In general Any election under this subsection for any taxable year— (i) shall specify the amount of the credit to which such election applies, (ii) shall be made on or before the due date (including extensions) of— (I) in the case of an eligible employer which is a partnership, the return required to be filed under section 6031, (II) in the case of an eligible employer which is an S corporation, the return required to be filed under section 6037, and (III) in the case of any other eligible employer, the return of tax for the taxable year, and (iii) may be revoked only with the consent of the Secretary. (B) Limitations The amount specified in any election made under this subsection shall not exceed $250,000. (C) Special rule for partnerships and s corporations In the case of an eligible employer which is a partnership or S corporation, the election made under this subsection shall be made at the entity level. (4) Aggregation rules (A) In general Except as provided in subparagraph (B), all persons or entities treated as a single taxpayer under subsection (e)(1) shall be treated as a single taxpayer for purposes of this subsection. (B) Special rules For purposes of this subsection and section 3111(g)— (i) each of the persons treated as a single taxpayer under subparagraph (A) may separately make the election under paragraph (1) for any taxable year, and (ii) the $250,000 amount under paragraph (3)(B)(i) shall be allocated among all persons treated as a single taxpayer under subparagraph (A) in the manner provided by the Secretary which is similar to the manner provided under section 41(f)(1). (5) Regulations The Secretary shall prescribe such regulations as may be necessary to carry out the purposes of this subsection, including— (A) regulations