Supplemental wages identified separately from regular wages
If you pay supplemental wages separately (or combine them in a single payment and specify the amount of each), the income tax withholding method depends partly on whether or not you withhold income tax from your employee’s regular wages:
If you withhold income tax from an employee’s regular wages, you can use one of the following methods for the supplemental wages : Withhold at the supplemental rates; see Publication NYS-50-T-NYS , New York State Withholding Tax Tables and Methods , Publication NYS-50-T-NYC , New York City Withholding Tax Tables and Methods , and Publication NYS-50-T-Y , Yonkers Withholding Tax Tables and Methods , (whichever apply) for the supplemental rates. Add the supplemental and regular wages for the most recent payroll period this year. Then figure the income tax withholding as if the total were a single payment. Subtract the tax already withheld from the regular wages. Withhold the remaining tax from the supplemental wages.
If you do not withhold income tax from the employee’s regular wages, use method b .