If the Secretary makes a determination or a proposed determination of the value of an item of property for purposes of the tax imposed under chapter 11, 12, or 13, he shall furnish, on the written request of the executor, donor, or the person required to make the return of the tax imposed by chapter 13 (as the case may be), to such executor, donor, or person a written statement containing the material required by subsection (b). Such statement shall be furnished not later than 45 days after the later of the date of such request or the date of such determination or proposed determination.
26 U.S. Code § 7517. Furnishing on request of statement explaining estate or gift valuation
(a) General rule
(b) Contents of statementA statement required to be furnished under subsection (a) with respect to the value of an item of property shall—
set forth any computation used in arriving at such value, and
contain a copy of any expert appraisal made by or for the Secretary.
(c) Effect of statement
“The amendments made by subsection (a) [enacting this section and amending sections 2031 and 2512 of this title]—
insofar as they relate to the tax imposed under chapter 12 of such Code [section 2501 et seq. of this title], shall apply to gifts made after December 31, 1976.”