percent of such costs paid or incurred by the taxpayer during any of the prior four taxable years. (b) Qualified installation cost For purposes of this section, the term qualified installation cost means, with respect to a taxpayer, amounts which are paid or incurred in the ordinary course of the taxpayer’s trade or business to install certified swine waste disposal technology. (c) Certified swine waste disposal technology The term certified swine waste disposal technology means environmentally sustainable technology certified under section 3(c) of the Swine Waste Infrastructure and Natural Environment Act . 45T. Swine waste disposal credit (a) In general For purposes of section 38, the swine waste disposal credit determined under this section with respect to a taxpayer for any taxable year is an amount equal to $100 for each 1,000 pounds of steady state live weight of swine waste disposed of in the ordinary course of the taxpayer’s trade or business using certified swine waste disposal technology (as such term is defined in section 45S) by the taxpayer during the taxable year. (b) Maximum credit (1) In general The aggregate credit determined under subsection (a) for any taxable year with respect to any taxpayer shall not exceed the qualified costs of the taxpayer for such taxable year. (2) Qualified costs defined For purposes of this section, the term qualified costs means costs paid or incurred by a taxpayer to maintain or operate certified swine waste disposal technology. . (b) Treatment as general business credit Subsection (b) of section 38 of such Code is amended by striking plus at the end of paragraph (35), by striking the period at the end of paragraph (36) and inserting a comma, and by adding at the end the following new paragraphs: (37) the swine waste disposal technology installation credit determined under section 45S(a), plus (38) the swine waste disposal credit determined under section 45T(a). . (c) Deduction for Unused Credit Subsection (c) of section 196 of such Code is amended by striking and