; but for purposes of this section allowances under section 167, and allowances under section 611, shall be considered as expenditures. (d) Exploration Expenditures This section shall not apply to any expenditure paid or incurred for the purpose of ascertaining the existence, location, extent, or quality of any deposit of ore or other mineral (including oil and gas). (e) Only Reasonable Research Expenditures Eligible This section shall apply to a research or experimental expenditure only to the extent that the amount thereof is reasonable under the circumstances. (f) Cross References (1) For adjustments to basis of property for amounts allowed as deductions as deferred expenses under subsection (b), see section 1016(a)(14). (2) For election of 10-year amortization of expenditures allowable as a deduction under subsection (a), see section 59(e). . (b) Change in method of accounting The amendments made by subsection (a) shall be treated as a change in method of accounting for purposes of section 481 of the Internal Revenue Code of 1986 and— (1) such change shall be treated as initiated by the taxpayer, (2) such change shall be treated as made with the consent of the Secretary, and (3) such change shall be applied only on a cut-off basis for any research or experimental expenditures paid or incurred in taxable years beginning after December 31, 2025, and no adjustments under section 481(a) shall be made. (c) Conforming amendments (1) Section 41(d)(1)(A), as amended by section 13206, is amended by striking specified research or experimental expenditures under section 174 and inserting expenses under section 174 . (2) Subsection (c) of section 280C , as amended by section 13206, is amended— (A) by redesignating paragraphs (2) and (3) as paragraphs (3) and (4), respectively, and (B) by striking paragraph (1) and inserting the following: (1) In general No deduction shall be allowed for that portion of the qualified research expenses (as defined in section 41(b)) or basic research expenses (as defined in section