Section, added Pub. L. 85–866, title II, § 206(a), Sept. 2, 1958, 72 Stat. 1681, § 6166; amended Pub. L. 93–625, § 7(d)(2), (3), Jan. 3, 1975, 88 Stat. 2115; renumbered § 6166A and amended Pub. L. 94–455, title XIX, § 1906(b)(13)(A), title XX, § 2004(a), Oct. 4, 1976, 90 Stat. 1834, 1862, provided for an extension of time for payment of estate tax where estate consists largely of interest in closely held business.

Repeal applicable to estates of decedents dying after Dec. 31, 1981, see section 422(f)(1) of Pub. L. 97–34, set out as an Effective Date of 1981 Amendment note under section 6166 of this title.