§ 6166. Extension of time for payment of estate tax where estate consists
largely of interest in closely held business
. . .
(b) Definitions and special rules
. . .

(7) Partnership interests and stock which is not readily tradable

(A) In general
If the executor elects the benefits of this paragraph (at such time and in such manner
as the Secretary shall by regulations prescribe), then—

(i) for purposes of paragraph (1)(B)(i) or (1)(C)(i) (whichever is appropriate) and
for purposes of subsection (c), any capital interest in a partnership and any non-
readily- tradable stock which (after the application of paragraph (2)) is treated as
owned by the decedent shall be treated as included in determining the value of the
decedent’s gross estate,
(ii) the executor shall be treated as having selected under subsection (a)(3) the
date prescribed by section 6151(a), and
(iii) for purposes of applying section 6601(j), the 2-percent portion (as defined in
such section) shall be treated as being zero.

(B) Non-readily-tradable stock defined
For purposes of this paragraph, the term ‘‘non-readily-tradable stock’’ means stock for which, at
the time of the decedent’s death, there was no market on a stock exchange or in an over-the-
counter market.