New York Codes, Rules and Regulations
Title 20 - DEPARTMENT OF TAXATION AND FINANCE
Chapter II - Income Taxes and Estate Taxes
Subchapter D - City Of Yonkers Earnings Tax On Nonresidents
Part 268 - Joint Collection And Enforcement Activity
Section 268.1 - Joint assessment of taxes and proportionate division of payment

Tax Law, § 1342; Codes and Ordinances of the City of Yonkers, § 92-113

If there is assessed a City of Yonkers earnings tax pursuant to article X of the Codes and Ordinances of the City of Yonkers, and there is also assessed a tax or taxes against the same taxpayer pursuant to article 22 of the Tax Law, chapter 17 or chapter 19 of title 11 of the Administrative Code of the City of New York or article IX of the Codes and Ordinances of the City of Yonkers, and payment of a single amount is required under the provisions of section 265.2 of this Title, such payment shall be deemed to have been made with respect to the taxes so assessed in proportion to the amount of such taxes due, including tax, penalties, interest and additions to tax. For the rate of interest on overpayments, underpayments and recovery of erroneous refunds, see Part 2393 of this Title.