Net State income tax deduction. For purposes of section 6362 (b)(1)(B) and (c)(3)(B), and §§ 301.6362-2 and 301.6362-3, the “net State income tax deduction” shall be the excess (if any) of (1) the amount deducted from income under section 164(a)(3) as taxes paid to a State or to a political subdivision thereof, over (2) the amounts included in income as recoveries of prior income taxes which were paid to a State or to a political subdivision thereof and which had been deducted under section 164(a)(3).

Net tax-exempt income. For purposes of section 6362 (b)(1)(C) and (c)(3)(A) and §§ 301.6362-2 and 301.6362-3, the “net tax-exempt income” shall be the excess (if any) of:

The sum of (i) the interest on obligations described in section 103 (a)(1) other than obligations of the State imposing the tax and the political subdivisions thereof, and (ii) the interest on obligations described in such section of such State and the political subdivisions thereof which under the law of the State is subject to the tax; over

The sum of (i) the amount of deductions allocable to the interest described in subparagraph (1) (i) or (ii) of this paragraph (b), which is disallowed pursuant to section 265 and the regulations thereunder, and (ii) the amount of the adjustment to basis allocable to such obligations which is required to be made for the taxable year under section 1016(a) (5) or (6).

Credits for taxes of other jurisdictions—(1) In general. A State tax law that provides for a credit, pursuant to section 6362(b)(2) (B) or (C) or section 6362(c)(4), and paragraph (b)(1) of § 301.6362-2 or paragraph (b)(2) of § 301.6362-3, for income tax of another State or a political subdivision thereof shall provide that, in the case of each taxpayer, the amount of the credit shall equal the amount of his liability with respect to such other jurisdiction's tax for the taxable year which runs concurrently with, or which ends in, the taxable year used by the taxpayer for purposes of the State tax which provides for the credit. Such a credit may be allowed with respect to every income tax (whether or not qualified) imposed on the taxpayer by another State or a political subdivision thereof, or only with respect to certain of such taxes. However, for purposes of this paragraph, the amount which is treated as being the amount of the taxpayer's liability with respect to any such tax imposed by another jurisdiction shall not exceed the amount of liability for such tax which is both—

Reported to the taxing authorities responsible for collecting such other jurisdiction's tax, and

Substantiated pursuant to the requirements of paragraph (c)(1)(ii) of § 301.6361-1.

Limitation. The amount of any credit allowed for the taxable year pursuant to this paragraph shall not exceed the product of the amount of the resident tax against which the credit is allowed, as computed without subtracting any such credit, multiplied by a fraction the numerator of which is the amount of income subject to tax by both the State imposing the resident tax against which the credit is allowed and the other jurisdiction whose tax is being credited, and the denominator of which is the amount of income subject to tax by the State imposing the resident tax against which the credit is allowed. For purposes of the preceding sentence, “income subject to tax” means the amount of the taxpayer's adjusted gross income which is taken into account for purposes of computing tax liability; in the case of a qualified resident tax, an appropriate modification shall be made to take into account any adjustments which are made pursuant to paragraph (a)(1) and (3) of § 301.6362-2, or pursuant to paragraph (a)(2) or (b)(1)(ii) of § 301.6362-3.

Examples. The application of this paragraph may be illustrated by the following examples:

A, a calendar-year, cash-basis taxpayer, is a resident of State X throughout the taxable year. For such year, his adjusted gross income for Federal income tax purposes consists of $24,000, consisting of $3,000 derived from employment in State X, $5,000 derived from employment in State Y. $15,000 derived from employment in State Z, and $1,000 in interest income from United States savings bonds. In addition, he received net tax-exempt income in the amount of $2,000. For the taxable year, he incurs liabilities of $200 for the State Y nonresident income tax, and $1,400 for the State Z nonresident income tax. State X, which has in effect a State agreement for the taxable year, imposes a resident tax against which credits are allowed for the nonresident taxes imposed by States Y and Z. Without taking any such credits into account, however, the amount of A's liability for such resident tax would be $1,500. A properly reports his nonresident income tax liabilities to States Y and Z at the same time that he files his return with respect to the State X tax, and he substantiates on such return his liabilities to States Y and Z.

The amount of A's income subject to tax in State X is $25,000 (his adjusted gross income of $24,000, minus the United States savings bond income of $1,000, plus the net tax-exempt income of $2,000). The amount of the credit allowable against the State X resident tax for the amount of A's liability with respect to the State Y nonresident tax is calculated as follows: The maximum amount of credit is the actual amount of his liability to Y, or $200. Under subparagraph (2) of this paragraph, the amount of the credit is limited to $300 ($1,500 × $5,000/$25,000). Thus, such limit has no effect, and the full $200 is allowable as a credit against A's liability for the resident tax of State X. The amount of the credit allowable against the State X resident tax for the amount of A's liability with respect to the State Z nonresident tax is calculated as follows: The maximum amount of the credit is the actual amount of his liability to Z, or $1,400. Under subparagraph (2) of this paragraph, the amount of the credit is limited to $900 (1,500 × $15,000/$25,000). Thus, such limit has the effect of reducing to $900 the amount of the credit allowable for tax of State Z against A's liability for the resident tax of State X.

B, a calendar-year, cash-basis taxpayer, is a resident of State X employed in State Y through March 14, 1977. On March 15, 1977, B becomes a resident of State Z and remains a resident of such State through the remainder of 1977. For 1977, the amount of B's adjusted gross income for Federal income tax purposes is $20,000, consisting of $6,000 derived from employment in State Y which B held during the period of his residence in State X, $12,000 derived from employment in State Z which B held during the period of his residence in State Z, and $2,000 in interest income from various bank accounts. During 1977, B has no interest income from United States obligations, and no tax-exempt income. For 1977, B incurs a liability of $200 to State Y on account of its nonresident income tax imposed with respect to his $6,000 of income derived from sources within that State. State Z, which has in effect a State agreement for 1977, imposes a resident income tax on B which, if B had been a resident of State Z for all 1977, would amount to $1,200 prior to the allowance of any credits under this paragraph. However, by reason of paragraph (e)(1) of § 301.6362-6, B's liability for the resident tax of State Z, before taking into account credits allowed under this paragraph, is reduced to $960 ($1,200 × 292/365, or 4/5). Furthermore, State Z allows a credit for the nonresident tax imposed by State Y.

The amount of the credit allowable against the State Z resident tax for the amount of B's liability with respect to the State Y nonresident tax is calculated as follows: The maximum amount of the credit is the amount of his actual liability to State Y, or $200. Under subparagraph (2) of this paragraph, the amount of the credit is limited to $288 ($960 × $6,000/$20,000). Thus, such limit has no effect, and the full $200 is allowable as a credit for tax of State Y against B's liability for the resident tax of State Z.