N.Y. Yonkers Income Tax Surcharge Law § 15-105
Withholding of the City of Yonkers income tax surcharge from the wages of City of Yonkers residents shall commence January 1, 1985. With respect to payment of such wages made after December 31, 1984, a City of Yonkers income tax surcharge shall be withheld from all wages of City of Yonkers residents in the same manner and subject to the same requirements, to the greatest extent possible, as is provided in § 671 through and including § 678 of the New York State Tax Law, except that the term "aggregate amount" contained in § 674(a)(1), (2), (3) and (4) of the New York State Tax Law shall mean the aggregate of the aggregate amounts of New York State personal income tax, city personal income tax on residents authorized pursuant to Article 30 of the New York State Tax Law, City of Yonkers income tax surcharge on residents pursuant to this article, city earnings tax on nonresidents authorized pursuant to Article 2-E of the General City Law and City of Yonkers earnings tax on nonresidents pursuant to Article X of this chapter to be deducted and withheld.
N.Y. Yonkers Income Tax Surcharge § 15-105