26 U.S.C. § 2102: Credits against tax

The tax imposed by section 2101 shall be credited with the amounts determined in accordance with sections 2012 and 2013 (relating to gift tax and tax on prior transfers). A credit of $13,000 shall be allowed against the tax imposed by section 2101. $13,000, or that proportion of $46,800 which the value of that part of the decedent’s gross estate which at the time of his death is situated in the United States bears to the value of his entire gross estate wherever situated. To the extent required under any treaty obligation of the United States, the credit allowed under this subsection shall be equal to the amount which bears the same ratio to the applicable credit amount in effect under section 2010(c) for the calendar year which includes the date of death as the value of the part of the decedent’s gross estate which at the time of his death is situated in the United States bears to the value of his entire gross estate wherever situated. For purposes of the preceding sentence, property shall not be treated as situated in the United States if such property is exempt from the tax imposed by this subchapter under any treaty obligation of the United States. If a credit has been allowed under section 2505 with respect to any gift made by the decedent, each dollar amount contained in paragraph (1) or (2) or subparagraph (A) of this paragraph (whichever applies) shall be reduced by the amount so allowed. The credit allowed under this subsection shall not exceed the amount of the tax imposed by section 2101. For purposes of subsection (a), sections 2012 and 2013 shall be applied as if the credit allowed under this subsection were allowed under section 2010.