Payroll deductions are wages withheld from an employee’s total earnings for the purposes of paying taxes, garnishments, and benefits. These withholdings constitute the difference between gross pay and net pay. Some payroll deductions, like EWA, are voluntary and may be taken out of a paycheck on a pretax or post-tax basis as long as the employee provided written authorization. Taxes and wage garnishments, on the other hand, are mandatory and employers who fail to accurately withhold these deductions may be liable for the missing amounts.

source: ADP