N.Y. Comp. Codes R. & Regs. tit. 20 § 262.4
Tax Law, § 4(c) of § 1340(c); Codes and Ordinances of the City of Yonkers, § 92-101(c)
The provisions of sections 262.1 through 262.3 of this Part are designed to apportion and allocate to the City of Yonkers, in a fair and equitable manner, a nonresident taxpayer's portion of wages and net earnings from self-employment attributable to a business, trade, profession or occupation carried on partly within and partly without the City of Yonkers. Where the methods provided under those sections do not so allocate and apportion such wages and net earnings from self-employment, the State Tax Commission may require a nonresident taxpayer to apportion and allocate wages and net earnings from self-employment under such method as it prescribes, as long as the prescribed method results in a fair and equitable apportionment and allocation. A nonresident may submit an alternative method of apportionment and allocation with respect to the portion of wages and net earnings from self-employment attributable to a business, trade, profession or occupation carried on partly within and partly without the City of Yonkers. The proposed method must be fully explained in the taxpayer's City of Yonkers earnings tax return. If the method proposed by the taxpayer is approved by the State Tax Commission, it may be used in lieu of the applicable method under sections 262.1 through 262.3 of this Part.
N.Y. Comp. Codes R. & Regs. Tit. 20 § 262.4