Form NC-4 Employee's Withholding Allowance Certificate. Employer: complete this section only if you must send a copy of this form to the New York State Tax Department (see instructions).Employer name and address. Withholding Tax Forms and Instructions To ensure you are able to view and fill out forms, please save forms to your computer and use the latest. PURPOSE - Complete Form NC-4, Employee's Withholding Allowance. Certificate, so that your employer can withhold the correct amount of. It is used to determine the amount of state income tax that should be withheld from each employee's paycheck. This document provides comprehensive instructions on filling out Form IT-2104, the Employee's Withholding Allowance Certificate. Form IT2104, Employee's Withholding Allowance Certificate. Reflecting the legislative interest in a more complete form of justice.