26 U.S.C. § 2207A — Right of recovery in the case of certain marital deduction property

(a) Recovery for estate tax
(1) In general 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 is entitled to recover from the person receiving the property the amount by which— (A) the total tax under this chapter which has been paid, exceeds
(B) the total tax under this chapter which would have been payable if the value of that property had not been included in the gross estate.
(2) Decedent may otherwise direct Paragraph
(1) must not apply for 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 for that property.

(b) Recovery for gift tax If for any calendar year tax is paid under chapter 12 for any person by reason of property treated as transferred by that person under section 2519, that person is entitled to recover from the person receiving the property the amount by which— (1) the total tax for that year under chapter 12, exceeds
(2) the total tax which would have been payable under that chapter for that year if the value of that property had not been taken into account for chapter 12.

(c) More than one recipient of property for this section, if there is more than one person receiving the property, the right of recovery is against each that person.

(d) Taxes and interest 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) must apply.