26 USC 2522 - Charitable and similar gifts

(a) Citizens or residents 
In computing taxable gifts for the calendar year, there shall be allowed as a deduction in the case of a citizen or resident the amount of all gifts made during such year to or for the use of
(1) the United States, any State, or any political subdivision thereof, or the District of Columbia, for exclusively public purposes;
(2) a corporation, or trust, or community chest, fund, or foundation, 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 involve the provision of athletic facilities or equipment), including the encouragement of art and the prevention of cruelty to children or animals, no part of the net earnings of which inures to the benefit of any private shareholder or individual, 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;
(3) a fraternal society, order, or association, operating under the lodge system, but only if such gifts are to be used exclusively for religious, charitable, scientific, literary, or educational purposes, including the encouragement of art and the prevention of cruelty to children or animals;
(4) posts or organizations of war veterans, or auxiliary units or societies of any such posts or organizations, if such posts, organizations, units, or societies are organized in the United States or any of its possessions, and if no part of their net earnings insures to the benefit of any private shareholder or individual.

Rules similar to the rules of section 501 (j) shall apply for purposes of paragraph (2).

(b) Nonresidents 
In the case of a nonresident not a citizen of the United States, there shall be allowed as a deduction the amount of all gifts made during such year to or for the use of
(1) the United States, any State, or any political subdivision thereof, or the District of Columbia, for exclusively public purposes;
(2) a domestic corporation organized and operated exclusively for religious, charitable, scientific, literary, or educational purposes, including the encouragement of art and the prevention of cruelty to children or animals, no part of the net earnings of which inures to the benefit of any private shareholder or individual, 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;
(3) a trust, or community chest, fund, or foundation, organized and operated exclusively for religious, charitable, scientific, literary, or educational purposes, including the encouragement of art and the prevention of cruelty to children or animals, no substantial part of the activities of which is carrying on propaganda, or otherwise 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; but only if such gifts are to be used within the United States exclusively for such purposes;
(4) a fraternal society, order, or association, operating under the lodge system, but only if such gifts are to be used within the United States exclusively for religious, charitable, scientific, literary, or educational purposes, including the encouragement of art and the prevention of cruelty to children or animals;
(5) posts or organizations of war veterans, or auxiliary units or societies of any such posts or organizations, if such posts, organizations, units, or societies are organized in the United States or any of its possessions, and if no part of their net earnings inures to the benefit of any private shareholder or individual.
(c) Disallowance of deductions in certain cases 

(1) No deduction shall be allowed under this section for a gift to of[1] for the use of an organization or trust described in section 508 (d) or 4948 (c)(4) subject to the conditions specified in such sections.
(2) Where a donor transfers an interest in property (other than an interest described in section 170 (f)(3)(B)) to a person, or for a use, described in subsection (a) or (b) and an interest in the same property is retained by the donor, or is transferred or has been transferred (for less than an adequate and full consideration in money or moneys worth) from the donor to a person, or for a use, not described in subsection (a) or (b), no deduction shall be allowed under this section for the interest which is, or has been transferred to the person, or for the use, described in subsection (a) or (b), unless
(A) in the case of a remainder interest, such interest is in a trust which is a charitable remainder annuity trust or a charitable remainder unitrust (described in section 664) or a pooled income fund (described in section 642 (c)(5)), or
(B) in the case of any other interest, such interest is in the form of a guaranteed annuity or is a fixed percentage distributed yearly of the fair market value of the property (to be determined yearly).
(3) Rules similar to the rules of section 2055 (e)(4) shall apply for purposes of paragraph (2).
(4) Reformations to comply with paragraph (2) 

(A) In general 
A deduction shall be allowed under subsection (a) in respect of any qualified reformation (within the meaning of section 2055 (e)(3)(B)).
(B) Rules similar to section 2055 (e)(3) to apply 
For purposes of this paragraph, rules similar to the rules of section 2055 (e)(3) shall apply.
(5) Contributions to donor advised funds 
A deduction otherwise allowed under subsection (a) for any contribution to a donor advised fund (as defined in section 4966 (d)(2)) shall only be allowed if
(A) the sponsoring organization (as defined in section 4966 (d)(1)) with respect to such donor advised fund is not
(i) described in paragraph (3) or (4) of subsection (a), or
(ii) a type III supporting organization (as defined in section 4943 (f)(5)(A)) which is not a functionally integrated type III supporting organization (as defined in section 4943 (f)(5)(B)), and
(B) the taxpayer obtains a contemporaneous written acknowledgment (determined under rules similar to the rules of section 170 (f)(8)(C)) from the sponsoring organization (as so defined) of such donor advised fund that such organization has exclusive legal control over the assets contributed.
(d) Special rule for irrevocable transfers of easements in real property 
A deduction shall be allowed under subsection (a) in respect of any transfer of a qualified real property interest (as defined in section 170 (h)(2)(C)) which meets the requirements of section 170 (h) (without regard to paragraph (4)(A) thereof).
(e) Special rules for fractional gifts 

(1) Denial of deduction in certain cases 

(A) In general 
No deduction shall be allowed for a contribution of an undivided portion of a taxpayers entire interest in tangible personal property unless all interests in the property are held immediately before such contribution by
(i) the taxpayer, or
(ii) the taxpayer and the donee.
(B) Exceptions 
The Secretary may, by regulation, provide for exceptions to subparagraph (A) in cases where all persons who hold an interest in the property make proportional contributions of an undivided portion of the entire interest held by such persons.
(2) Recapture of deduction in certain cases; addition to tax 

(A) In general 
The Secretary shall provide for the recapture of an amount equal to any deduction allowed under this section (plus interest) with respect to any contribution of an undivided portion of a taxpayers entire interest in tangible personal property
(i) in any case in which the donor does not contribute all of the remaining interests in such property to the donee (or, if such donee is no longer in existence, to any person described in section 170 (c)) on or before the earlier of
(I) the date that is 10 years after the date of the initial fractional contribution, or
(II) the date of the death of the donor, and
(ii) in any case in which the donee has not, during the period beginning on the date of the initial fractional contribution and ending on the date described in clause (i)
(I) had substantial physical possession of the property, and
(II) used the property in a use which is related to a purpose or function constituting the basis for the organizations exemption under section 501.
(B) Addition to tax 
The tax imposed under this chapter for any taxable year for which there is a recapture under subparagraph (A) shall be increased by 10 percent of the amount so recaptured.
(C) Initial fractional contribution 
For purposes of this paragraph, the term initial fractional contribution means, with respect to any donor, the first gift of an undivided portion of the donors entire interest in any tangible personal property for which a deduction is allowed under subsection (a) or (b).
(f) Cross references 

(1) For treatment of certain organizations providing child care, see section 501 (k).
(2) For exemption of certain gifts to or for the benefit of the United States and for rules of construction with respect to certain bequests, see section 2055 (f).
(3) For treatment of gifts to or for the use of Indian tribal governments (or their subdivisions), see section 7871.
[1] So in original. Probably should be “or”.