Coordination with other chapters—(1) In general. Subchapter C of chapter 63 of the Internal Revenue Code (subchapter C of chapter 63) only applies to tax imposed by chapter 1 of the Internal Revenue Code (Code) and not to any tax imposed (including any amount required to be deducted or withheld) under any chapter of the Code other than chapter 1 of the Code (chapter 1), including chapter 2, 2A, 3, or 4 of the Code. Accordingly, for purposes of determining taxes imposed under chapters of the Code other than chapter 1, the Internal Revenue Service (IRS) may make an adjustment to any partnership-related item (as defined in § 301.6241-1(a)(6)(ii)) in a proceeding that is not under subchapter C of chapter 63. To the extent an adjustment or determination is made under subchapter C of chapter 63 for purposes of chapter 1 and is relevant in determining tax imposed under a chapter of the Code other than chapter 1, such adjustment or determination must be taken into account for purposes of determining such tax.

Examples. The following examples illustrate the rules of paragraph (a) of this section as applied to cases in which a partnership has a withholding obligation under chapter 3 or chapter 4 with respect to income that the partnership earns. For purposes of these examples, each partnership is subject to the provisions of subchapter C of chapter 63 of the Code, and the partnership and its partners are calendar year taxpayers.

Example 1. Partnership, a partnership created or organized in the United States, has two equal partners, A and B. A is a nonresident alien who is a resident of Country A, and B is a U.S. citizen. In 2018, Partnership earned $200 of U.S. source royalty income. Partnership was required to withhold 30 percent of the gross amount of the royalty income allocable to A unless Partnership had documentation that it could rely on to establish that A was entitled to a reduced rate of withholding. See §§ 1.1441-1(b)(1) and 1.1441-5(b)(2)(i)(A) of this chapter. Partnership withheld $15 from the $100 of royalty income allocable to A based on its incorrect belief that A is entitled to a reduced rate of withholding under the U.S.-Country A Income Tax Treaty. In 2020, the IRS determines in an examination of Partnership's Form 1042, Annual Withholding Tax Return for U.S. Source Income of Foreign Persons, that Partnership should have withheld $30 instead of $15 on the $100 of royalty income allocable to A because Partnership failed to obtain documentation from A establishing a valid treaty claim for a reduced rate of withholding. The tax imposed on Partnership for its failure to withhold on that income, however, is not a tax imposed by chapter 1. Rather, it is a tax imposed by chapter 3, which is not a partnership-related item under § 301.6241-1(a)(6)(ii). Therefore, in accordance with section 6221(a), the adjustment to increase Partnership's withholding tax liability by $15 is not determined under subchapter C of chapter 63, and instead must be determined as part of the Form 1042 examination.

Example 2. Partnership, a partnership created or organized in the United States, has two equal partners, A and B. A is a nonresident alien who is a resident of Country A, and B is a U.S. citizen. In 2018, Partnership earned $100 of U.S. source dividend income. Partnership was required to report the dividend income on its 2018 Form 1065, U.S. Return of Partnership Income, and withhold 30 percent of the gross amount of the dividend income allocable to A unless Partnership had documentation that it could rely on to establish that A was entitled to a reduced rate of withholding. See §§ 1.1441-1(b)(1) and 1.1441-5(b)(2)(i)(A) of this chapter. In 2020, in an examination of Partnership's Form 1042, the IRS determines that Partnership earned but failed to report the $100 of U.S. source dividend income in 2018. The adjustment to increase Partnership's dividend income by $100 is an adjustment to a partnership-related item. The tax imposed on Partnership for its failure to withhold on that income, however, is not a tax imposed by chapter 1; rather, it is a tax imposed by chapter 3. Pursuant to § 301.6221(a)-1(a), only chapter 1 tax attributable to adjustments to partnership-related items is assessed under subchapter C of chapter 63. Therefore, because the tax imposed with respect to the adjustment is a chapter 3 tax, under paragraph (a)(1) of this section, the IRS may determine, assess, and collect chapter 3 tax attributable to an adjustment to a partnership-related item without conducting a proceeding under subchapter C of chapter 63. Accordingly, the IRS may determine the chapter 3 tax in the examination of Partnership's Form 1042 by adjusting Partnership's withholding tax liability by an additional $15 for failing to withhold on the $50 of dividend income allocable to A. However, the IRS must initiate an administrative proceeding under subchapter C of chapter 63 to make any adjustments for purposes of chapter 1 attributable to the income. If the IRS subsequently initiates an administrative proceeding under subchapter C of chapter 63 and makes an adjustment to the same item of income, the portion of the dividend income allocable to A will be disregarded in the calculation of the total netted partnership adjustment to the extent that the chapter 3 tax has been collected with respect to such income. See § 301.6225-1(b)(3).

Coordination with chapters 3 and 4—(1) In general. In the case of any tax imposed under chapter 3 or chapter 4 that is determined with respect to a partnership adjustment determined under subchapter C of chapter 63 for purposes of chapter 1, such tax is determined with respect to the reviewed year (as defined in § 301.6241-1(a)(8)) and is imposed (or required to be deducted and withheld) with respect to the adjustment year (as defined in § 301.6241-1(a)(1)).

Definitions. The following definitions apply for purposes of this paragraph (b) and the regulations under subchapter C of chapter 63.

Amount subject to withholding. The term amount subject to withholding means an amount subject to withholding (as defined in § 1.1441-2(a) of this chapter), a withholdable payment (as defined in § 1.1473-1(a) of this chapter), or the allocable share of effectively connected taxable income (as computed under § 1.1446-2(b) of this chapter).

Chapter 3. The term chapter 3 means sections 1441 through 1464 of the Code, but does not include section 1443(b) of the Code.

Chapter 4. The term chapter 4 means sections 1471 through 1474 of the Code.

Partnership pays an imputed underpayment. If a partnership pays an imputed underpayment (as determined under § 301.6225-1(b)) and the total netted partnership adjustment (as calculated under § 301.6225-1(b)(2)) includes a partnership adjustment to an amount subject to withholding, the partnership is treated as having paid (at the time that the imputed underpayment is paid) the amount required to be withheld with respect to that partnership adjustment under chapter 3 or chapter 4 for purposes of applying §§ 1.1463-1 and 1.1474-4 of this chapter. See § 301.6225-1(b)(3) for the coordination rule that applies for calculating an imputed underpayment when an adjustment is made to an amount subject to withholding for which tax has been collected under chapter 3 or chapter 4.

Partnership makes an election under section 6226 with respect to an imputed underpayment—(i) In general. A partnership that makes an election under § 301.6226-1 with respect to an imputed underpayment must pay the amount of tax required to be withheld under chapter 3 or chapter 4 on the amount of any adjustment set forth in the statement described in § 301.6226-2(a) to the extent that it is an adjustment to an amount subject to withholding, and the IRS has not already collected tax attributable to the adjustment under chapter 3 or chapter 4. The partnership must pay the amount due under this paragraph (b)(4)(i) on or before the due date of the partnership return for the adjustment year (without regard to extension), and must make the payment in the manner prescribed by the IRS in forms, instructions, and other guidance. For the rules governing partners subject to the taxes imposed by chapters 3 and 4 when the partner receives a statement under § 301.6226-2, see § 301.6226-3(f). See § 301.6226-3(e)(3)(v) for the application of the rules of this paragraph (b)(4) to pass-through partners (as defined in § 301.6241-1(a)(5)).

Reduced rate of tax. A partnership may reduce the amount of tax it is required to pay under paragraph (b)(4)(i) of this section to the extent that it can associate valid documentation from a reviewed year partner pursuant to the regulations under chapter 3 or chapter 4 (other than pursuant to § 1.1446-6 of this chapter) with the portion of the adjustment that would have been subject to a reduced rate of tax in the reviewed year. For this purpose, the partnership may rely on documentation that the partnership possesses that is valid with respect to the reviewed year (determined without regard to the expiration after the reviewed year of any validity period prescribed in § 1.1441-1(e)(4)(ii), § 1.1446-1(c)(2)(iv)(A), or § 1.1471-3(c)(6)(ii) of this chapter), or new documentation that the partnership obtains from the reviewed year partner that includes a signed affidavit stating that the information and representations associated with the documentation are accurate with respect to the reviewed year.

Reporting requirements. A partnership required to pay tax under paragraph (b)(4)(i) of this section must file the appropriate return and issue information returns as required by regulations under chapter 3 or chapter 4. For return and information return requirements, see §§ 1.1446-3(d)(1)(iii); 1.1461-1(b), (c); and 1.1474-1(c), (d) of this chapter. The partnership must file the return and issue information returns for the year that includes the date on which the partnership pays the tax required to be withheld under paragraph (b)(4)(i) of this section. The partnership must report the information on the return and information returns in the manner prescribed by the IRS in forms, instructions, and other guidance.

Partners subject to withholding. A reviewed year partner that is subject to withholding under paragraph (b)(4)(i) of this section must follow the rules under § 301.6226-3(f).

Applicability date—(1) In general. Except as provided in paragraph (c)(2) of this section, this section applies to partnership taxable years beginning after December 31, 2017, and ending after August 12, 2018.

Election under § 301.9100-22 in effect. This section applies to any partnership taxable year beginning after November 2, 2015, and before January 1, 2018, for which a valid election under § 301.9100-22 is in effect.