1. Short title This Act may be cited as the WALL Act of 2018 . 2. Mandatory spending for border wall (a) In general There is appropriated $25,000,000,000 for the purpose of constructing a physical barrier along the southern border of the United States. (b) Availability Amounts appropriated under subsection (a) shall remain available until expended for the purpose described in subsection (a). 3. Offsets (a) Eligibility for child tax credit (1) In general Section 24(e) of the Internal Revenue Code of 1986 is amended to read as follows: (e) Identification requirements (1) In general No credit shall be allowed under this section to a taxpayer with respect to any qualifying child unless the taxpayer includes on the return of tax for the taxable year— (A) the name of such qualifying child, and (B) the valid identification number of the taxpayer (and, in the case of a joint return, the taxpayer’s spouse) and such qualifying child. (2) Valid identification number (A) In general For purposes of this subsection, the term valid identification number means— (i) in the case of the taxpayer and any spouse of the taxpayer, a social security number issued to the individual by the Social Security Administration on or before the due date for filing the return for the taxable year, and (ii) in the case of a qualifying child, a social security number issued to such child by the Social Security Administration on or before the due date for filing such return. (B) Exception for individuals prohibited from engaging in employment in United States For purposes of subparagraph (A)(i) and subsection (h)(4)(C), the term social security number shall not include the social security number of an individual who is prohibited from engaging in employment in the United States. . (2) Conforming amendments Subsection (h) of section 24 of the Internal Revenue Code of 1986 is amended— (A) in paragraph (1), by striking (7) and inserting (6)