No, your employer may not do this. Employees must be paid their full, agreed-upon wage or salary for the work they do, and employers may not deduct or withhold from those wages/salary unless 1) the employee him- or herself consents to the deduction; or 2) the deduction is one mandated by law (such as FICA withholding; court-ordered wage garnishment). Otherwise, if an employee did not fill out some survey which the employer wished him or her to fill out, the employer could suspend, demote, even terminate the employee--but may not legally withhold wages.