26 U.S.C. § 2207A

1. (a)
   1. (1)If any part of the gross estate consists of property the value of which is includible in the gross estate by reason of section 2044 (relating to certain property for which marital deduction was previously allowed), the decedent’s estate shall be entitled to recover from the person receiving the property the amount by which—
      1. (A)the total tax under this chapter which has been paid, exceeds
      2. (B)the total tax under this chapter which would have been payable if the value of such property had not been included in the gross estate.
   2. (2)Paragraph (1) shall not apply with respect to any property to the extent that the decedent in his will (or a revocable trust) specifically indicates an intent to waive any right of recovery under this subchapter with respect to such property.
2. (b)If for any calendar year tax is paid under chapter 12 with respect to any person by reason of property treated as transferred by such person under section 2519, such person shall be entitled to recover from the person receiving the property the amount by which—
   1. (1)the total tax for such year under chapter 12, exceeds
   2. (2)the total tax which would have been payable under such chapter for such year if the value of such property had not been taken into account for purposes of chapter 12.
3. (c)For purposes of this section, if there is more than one person receiving the property, the right of recovery shall be against each such person.
4. (d)In the case of penalties and interest attributable to additional taxes described in subsections (a) and (b), rules similar to subsections (a), (b), and (c) shall apply.