26 U.S.C. § 873: Deductions

In the case of a nonresident alien individual, the deductions shall be allowed only for purposes of section 871(b) and (except as provided by subsection (b)) only if and to the extent that they are connected with income which is effectively connected with the conduct of a trade or business within the United States; and the proper apportionment and allocation of the deductions for this purpose shall be determined as provided in regulations prescribed by the Secretary. The deduction allowed by section 165 for casualty or theft losses described in paragraph (2) or (3) of section 165(c), but only if the loss is of property located within the United States. The deduction for charitable contributions and gifts allowed by section 170. The deduction for personal exemptions allowed by section 151, except that only one exemption shall be allowed under section 151 unless the taxpayer is a resident of a contiguous country or is a national of the United States. For rule that certain foreign taxes are not to be taken into account in determining deduction or credit, see section 906(b)(1).