Section 6166(b)(1)(B) provides:
(b) Definitions and special rules
(1) Interest in closely held business
For purposes of this section, the term "interest in a closely held business" means-
. . . . . . . . . . . .
(B) an interest as a partner in a partnership carrying on a trade or business, if-
(i) 20 percent or more of the total capital interest in such partnership is included in determining the gross estate of the decedent, or
(ii) such partnership had 45 or fewer partners;