• A wage deduction can be statutory or voluntary.Comstock/Comstock/Getty Images
  
  Statutory deductions are those the employer is legally required to make from employees' wages, such as payroll taxes, and if applicable, wage garnishments and child support. Deductions can also be voluntary -- the employee consents to these types of deductions. Limits on wage deductions depend on the type of deduction.
  
  

Federal Income Tax

• Employers are required to withhold federal income tax from all employees' wages, except if the employees claims, and qualifies for, exempt status. Federal income tax does not have one set limit that applies to each employee. The limit depends on the employee's claimed allowances and filing status, as shown on her W-4 form. IRS Circular E gives the maximum amount of federal income tax to withhold based on the employee's pay period, filing status, allowances, and gross wages.
  
  

Social Security Tax

• Social Security tax applies to all employees, except if an exception applies, such as a non-immigrant employee with a certain type of visa. Social Security tax funds the Old-Age, Survivors, and Disability Insurance program, which limits the amount of wages subject to taxation for the year. The annual wage limit for 2009, 2010, and 2011 is $106,800. Once the employee satisfies this amount, the employer ceases the withholding until the new year begins. The employer withholds Social Security tax at 6.2 percent of gross wages, up to the yearly wage limit.
  
  

Wage Garnishments

• A wage garnishment is a legal document that orders an employer to withhold a certain portion of an employee's wages to satisfy a debt he owes. Title III of the Consumer Credit Protection Act limits the amount an employer can deduct for a wage garnishment. For ordinary garnishments, such as those a creditor initiates, the employer can garnish up to 25 percent of disposable income in a single pay period. Disposable income is the employee's pay after payroll taxes and voluntary pre-tax deductions have been withheld.
  
  

Child Support/Alimony

• Title III also limits the amount an employer can deduct for child support and alimony. If the employee is currently supporting a spouse or child outside of the support order, the employer can withhold up to 50 percent of disposable income; if not, it can withhold up to 60 percent. It can deduct an additional five percent for support payment more than 12 weeks overdue.
  
  

401(k)

• An employee can contribute only so much of his wages toward his 401(k) plan within a single year. For 2010 and 2011, the limit for a safe harbor or traditional 401(k) plan is $16,500. The limit for a SIMPLE 401(k) plan is $11,500. Employees 50 or older can contribute an additional $5,500 for the year toward a traditional or safe harbor plan, and an additional $2,500 toward a SIMPLE 401(k) plan. According to the IRS, these limits may be subject to a cost of living increase after 2011. The employee does not have to contribute the entire limit for the year. The minimum depends on the employer's plan document. For example, the plan document may require a minimum contribution of three percent of gross wages.