(1) Income taxes In the case of any tax imposed by subtitle A— (A) General rule If the taxpayer omits from gross income an amount properly includible therein and— (i) such amount is in excess of 25 percent of the amount of gross income stated in the return, or (ii) such amount— (I) is attributable to one or more assets with respect to which information is required to be reported under section 6038D (or would be so required if such section were applied without regard to the dollar threshold specified in subsection (a) thereof and without regard to any exceptions provided pursuant to subsection (h)(1) thereof), and (II) is in excess of $5,000, the tax may be assessed, or a proceeding in court for collection of such tax may be begun without assessment, at any time within 6 years after the return was filed. (B) Determination of gross income For purposes of subparagraph (A)— (i) In the case of a trade or business, the term “gross income” means the total of the amounts received or accrued from the sale of goods or services (if such amounts are required to be shown on the return) prior to diminution by the cost of such sales or services; (ii) An understatement of gross income by reason of an overstatement of unrecovered cost or other basis is an omission from gross income; and (iii) In determining the amount omitted from gross income (other than in the case of an overstatement of unrecovered cost or other basis), there shall not be taken into account any amount which is omitted from gross income stated in the return if such amount is disclosed in the return, or in a statement attached to the return, in a manner adequate to apprise the Secretary of the nature and amount of such item. (C) Constructive dividends If the taxpayer omits from gross income an amount properly includible therein under section 951(a), the tax may be assessed, or a proceeding in court for the collection of such tax may be done without assessing, at any time within 6 years after the return was filed.
26 USC § 6501(e)(1)
None identified, default scope is assumed to be the parent (subchapter A) of this section.