Social Security is both an employee withholding tax and an employer payroll tax. The employer is responsible for remitting a total of 12.4% of an employee's taxable earnings to the IRS. They are permitted to take 6.2% from the employee as a withholding tax and "match" the other 6.2% as a payroll tax. There is a wage base limit, which means that the tax stops at a certain amount of wages for the year. This varies per year. In 2019, the wage base limit was $137,700, this is the same for 2020.