TITLE 26, Subtitle A, Chapter 1, Subchapter F, Part 1, Sec. 501
Sec. 501.- Exemption from tax on corporations, certain trusts, etc.
(c) List of exempt organizations
(2) Corporations organized for the exclusive purpose of holding title to property, collecting income there from, and turning over the entire amount thereof, less expenses, to an organization which itself is exempt under this section. Rules similar to the rules of subparagraph (G) of paragraph (25) shall apply for purposes of this paragraph.
The possible question of whether or not the irrevocable charitable trust would qualify under the above exemption is addressed by:
TITLE 26, Subtitle D, Chapter 42, Subchapter A, Sec. 4947
Sec. 4947.- Application of taxes to certain nonexempt trusts
(a) Application of tax
(1) Charitable trusts
For purposes of part II of subchapter F of chapter 1 (other than section 508(a), (b), and (c)) and for purposes of this chapter, a trust which is not exempt from taxation under section 501(a), all of the unexpired interests in which are devoted to one or more of the purposes described in section 170(c)(2)(B), and for which a deduction was allowed under section 170, 545(b)(2), 556(b)(2),642(c),2055, 2106(a)(2), or 2522 (or the corresponding provisions of prior law), shall be treated as an organization described in section 501(c)(3). For purposes of section 509(a)(3)(A), such a trust shall be treated as if organized on the day on which it first becomes subject to this paragraph.
The above Sec. 4947 directs us to Sec. 170(c)(2)(B) which establishes the trusts as tax exempt:
TITLE 26, Subtitle A, CHAPTER 1, Subchapter B, Part VI, Sec. 170.
Sec. 170.- Charitable, etc., contributions and gifts
(c) Charitable contribution defined:
For purposes of this section, the term “charitable contribution” means a contribution or gift to or for the use of –
(2) A corporation, trust, or community chest, fund, or foundation –
(B) organized and operated exclusively for religious, charitable, scientific, literary, or educational purposes, or to foster national or international amateur sports competition (but only if no part of its activities involves the provision of athletic facilities or equipment), or for the prevention of cruelty to children or animals;
(C) no part of the net earnings of which inures to the benefit of any private shareholder or individual; and
(D) which is not disqualified for tax exemption under section 501(c)(3) by reason of attempting to influence legislation, and which does not participate in, or intervene in (including the publishing or distributing of statements), any political campaign on behalf of (or in opposition to) any candidate for public office.