1. (1) Where a resident individual receives income derived from sources within another state of the United States, a political subdivision of another state, the District of Columbia, or a province of Canada, such resident individual is entitled to a credit against his or her ordinary tax (see section 101.1 of this Title) for any income tax imposed on such income by the other jurisdiction. The term income tax imposed, as used in this section and in sections 120.2 through 120.5 of this Part, does not include the portion of such tax (determined in accordance with the provisions of section 120.6[b] of this Part) imposed on the ordinary income portion (or part thereof) of a lump sum distribution which is subject to the separate tax imposed by section 603 of the Tax Law. (See section 120.6 of this Part for the credit allowable against the separate tax on the ordinary income portion [or part thereof] of a lump sum distribution.) A resident estate or trust is also entitled to a similar credit against ordinary tax, computed in the same way and subject to the same exception and limitations, set forth in this section and sections 120.2 through 120.5 of this Part, as in the case of a resident individual.

2. (2) The credit against ordinary tax is allowable only for that portion of the income tax imposed by another state of the United States, a political subdivision of another state, the District of Columbia, or a province of Canada (or both another state of the United States and also one or more of its political subdivisions) which is applicable to the income derived from sources within such other taxing jurisdiction. (See section 120.4[d] of this Part for the definition of the term income derived from sources within another jurisdiction, and subdivision [c] of such section for the definition of income tax imposed by the other jurisdiction.)

   (b) Method of claiming credit.

3. (1) If a resident individual claims a credit against ordinary tax under this Part, such resident individual must attach to his or her New York State personal income tax return the credit claim form.
4. (2) If two or more taxing jurisdictions (as defined in this paragraph) impose income taxes on the same or different amounts of income derived from sources within such taxing jurisdictions, a separate New York State credit claim form must be attached to the taxpayer's New York State personal income tax return for each jurisdiction for which credit is claimed. The term two or more taxing jurisdictions, as used in this section and in section 120.2 of this Part, means any combination of states (other than New York State), political subdivisions of different states (other than both a state and one or more of its political subdivisions as provided in paragraph [3] of this subdivision), the District of Columbia, and provinces of Canada.
5. (3) If both a state (other than New York State) and one or more of the political subdivisions of such state impose income taxes on the same or different amounts of income, derived from sources within such state and one or more of its political subdivisions, the sum of the income taxes paid to the state and its political subdivisions must be reported on a single credit claim form. (See also section 120.3 of this Part.)
6. (4) A resident estate or trust must also comply with the provisions of this subdivision in order to claim a credit for an income tax of another state, a political subdivision or subdivisions of another state, the District of Columbia, or a province or provinces of Canada.

Tax Law, § 620(a)

(a) General.