is social security taxes part of the federal income tax
Image source: Getty Images. Social Security tax is one part of the Federal Insurance Contribution Act (FICA) tax, and it is assessed at a rate of 12.4%. This is split evenly between the employee and employer, and it applies to earned income up to $118,500 for 2016 -- resulting in a maximum Social Security tax of $14,694. The remainder of FICA tax goes to Medicare.