N.Y. Comp. Codes R. & Regs. tit. 20 § 252.1
Tax Law, § 1332(c); Codes and Ordinances of the City of Yonkers, § 92-93&
The State Tax Commission may require (including by means of forms and instructions) the making and filing of a combined return, which return, in addition to the City of Yonkers income tax surcharge return required by section 1326 of the Tax Law and section 92-85 of the Codes and Ordinances of the City of Yonkers, may also include returns required to be made and filed under the provisions of article 22 of the Tax Law relating to New York State personal income tax, article 30 of the Tax Law and chapter 17 of title 11 of the Administrative Code of the City of New York relating to City of New York personal income tax on residents, article 2-E of the General City Law and chapter 19 of title 11 of the Administrative Code of the City of New York relating to City of New York earnings tax on nonresidents, and article 30-B of the Tax Law and article X of the Codes and Ordinances of the City of Yonkers relating to City of Yonkers earnings tax on nonresidents.
The State Tax Commission may require (including by means of forms and instructions) the filing of a combined employer's return, which return, in addition to the City of Yonkers employer's return required by section 1329 of the Tax Law and section 92-88 of the Codes and Ordinances of the City of Yonkers (see section 251.2 of this Title), may also include employer's returns required to be filed under the provisions of article 22 of the Tax Law relating to withheld New York State personal income tax, article 30 of the Tax Law and chapter 17 of title 11 of the Administrative Code of the City of New York relating to withheld City of New York personal income tax on residents, article 2-E of the General City Law and chapter 19 of title 11 of the Administrative Code of the City of New York relating to withheld City of New York earnings tax on nonresidents, and article 30-B of the Tax Law and article X of the Codes and Ordinances of the City of Yonkers relating to withheld City of Yonkers earnings tax on nonresidents.
N.Y. Comp. Codes R. & Regs. Tit. 20 § 252.1