Notice 2021-01, page 315.

This notice provides that, while subject to a delay, private foundations must electronically file Form 4720, Return of Certain Excise Taxes Under Chapters 41 and 42 of the Internal Revenue Code, as required by section 3101 of the Taxpayer First Act of 2019 (Pub. L. No. 116-25) amendments to section 6033 of the Internal Revenue Code. Private foundations may no longer rely on Treas. Reg. § 53.6011-1(c) as a result of this electronic filing mandate.