N.Y. Comp. Codes R. & Regs. tit. 20, § 158.4 – Records of employers and other persons required to file New York State information returns.

(a) Every employer or withholding agent, as defined for Federal income tax withholding purposes, required under section 671 of the Tax Law (see Part 171 of this Title) to deduct and withhold New York State personal income tax upon the wages of employees, and every person required to file New York State information returns pursuant to section 158.10 of this Part, must keep all records pertinent to withholding of New York State personal income tax and New York State information returns available for examination and inspection by the Department of Taxation and Finance, or its authorized representatives. Records with respect to New York State personal income tax withheld must be retained for a period of four years after the due date of the New York State personal income tax withheld for the return period to which the records relate, or the date the New York State personal income tax withheld was paid, whichever is later. Records with respect to any other New York State information returns must be retained for a period of four years after the due date of the New York State information return.
(b) No particular form is prescribed for the keeping of records of employers and other persons required to file New York State information returns. However, in the case of employers, the records should include the amounts and dates of all wage payments subject to New York State personal income tax, the names, addresses and occupations of employees receiving such payments, the periods of their employment, the periods for which they are paid by the employer while absent due to sickness or personal injuries and the amount and weekly rate of such payments, their social security account numbers, their income tax withholding exemption certificates, the employer's identification number, record of New York State employer withholding returns and reports filed, and the dates and amounts of New York State personal income tax withholding payments made.
(c) For nonresident employees performing services partly within and partly without New York State, a record of the allocation used for withholding purposes must be kept.
(d) See Part 2402 of this Title for taxpayer record retention formats.