not exceed the excess (if any) of— (A) $30,000, over (B) the aggregate amount allowed as a credit under subsection (a) to such taxpayer for all prior taxable years. (c) Definitions For purposes of this section— (1) Qualified individual The term qualified individual means an individual who has attained 60 years of age. (2) Qualified expenditure The term qualified expenditure means an expenditure for any of the following modifications installed on a qualified residence: (A) The installation of entrance and exit ramps. (B) The widening of doorways. (C) The installation of handrails or grab bars. (D) The installation of non-slip flooring. (E) A modification that is included in a list established and maintained in accordance with subsection (d)(2) . (3) Qualified residence The term qualified residence has the meaning given that term in section 163(h)(4)(A). (d) Special Rules (1) Labor costs Expenditures for labor costs properly allocable to the onsite preparation, assembly, or original installation of a modification described under subsection (c)(2) and for piping or wiring to interconnect such modification to the dwelling unit shall be taken into account for purposes of this section. (2) List of modifications The Secretary, in consultation with the Secretary of Health and Human Services and after receiving the input of members of the public (including seniors groups, health organizations, and social services organizations), shall establish and maintain a list of any modification that, if installed on a residence of a qualified individual, would enhance the ability of such individual to remain living safely, independently, and comfortably in such residence. (3) When expenditure made (A) In general Except as provided in subparagraph (B) , a qualified expenditure shall be treated as made when the original installation of the modification is completed. (B) Expenditures as part of building construction In the case of a qualified expenditure in connection with the construction or reconstruction of a structure, such