The employee's Social Security tax rate for 2013 is 6.2% of the first $113,700 of wages, salaries, etc. An employee's 2013 earnings in excess of $113,700 are not subject to the Social Security tax.

(For the years 2012 and 2011, the employee's Social Security tax rate was temporarily reduced to 4.2%. In those years the wage limits were slightly lower since they are adjusted annually for the change in the national average wage index.)

The Social Security tax is one component of what is known as the FICA payroll tax. The other component is the Medicare tax, which applies to every dollar of an employee's wages, salaries, etc. In other words, there is no wage limit or cap for the Medicare tax.

In addition to the employee's Social Security tax, there is also an employer's Social Security tax.