26 U.S.C. § 1446(f); 26 CFR § 1.1446(f)-2
Section 1446(f), added by the 2017 Tax Cuts and Jobs Act (Pub. L. 115-97, § 13501), requires a transferee acquiring a partnership interest from a foreign person to withhold 10 percent of the amount realized where any portion of the transferor's gain would be treated under Section 864(c)(8) as effectively connected with a U.S. trade or business. Final regulations (TD 9926, published in the Federal Register November 30, 2020; corrected March 8, 2021) set out the operative withholding mechanics, certifications, and exceptions for transfers of non-publicly-traded partnership interests, and apply to transfers occurring on or after January 29, 2021.
26 CFR § 1.1031(a)-3
26 CFR § 1.1031(k)-1
26 CFR §§ 1.1400Z2(a)-1 through 1.1400Z2(f)-1
26 U.S.C. § 1031
26 U.S.C. § 1250
26 U.S.C. § 1400Z-2
Pin a building and we'll surface every amendment, effective-date change, and filing deadline as it happens.