The maximum amount of an employee's 2015 earnings (and a self-employed person's net income) that is subject to the Social Security tax is $118,500. This amount is also known as the Social Security annual limit, wage base, contribution and benefit base, ceiling, tax cap, and maximum taxable earnings. The maximum amount is adjusted annually based on the national average wage index.

The combination of the Social Security tax and the Medicare tax is often referred to as the FICA tax. However, there is no annual limit or cap on the earnings for the Medicare tax. In other words, every dollar of wages, salaries, self-employed person's net income, etc. is subject to the Medicare tax.