All U.S. employers must complete and retain a Form I-9 for each individual they hire for employment in the United States. This includes citizens and noncitizens.
A person who is required to file an information return with the IRS must obtain your correct taxpayer identification number (TIN) to report, for example, income paid to you, real estate transactions, mortgage interest you paid, acquisition or abandonment of secured property, cancellation of debt, or contributions you made to an IRA.
The Form IT-2104 is completed by an employee so an employer can withhold the correct amount of NY State (and NYC and Yonkers) from your pay.
A tax form prepared by an employee for an employer indicating the employee’s exemptions and Social Security number, and enabling the employer to determine the amount of taxes to be withheld for the employee.