social security gets its money through payroll taxes. those taxes are called federal insurance contributions act tax (fica) or self employed contributions act tax (seca). tax deposits are collected by the internal revenue service (irs). almost all salaried income, up to an certain amount set by law (see tax rate table below), is taxed by the social security payroll tax. all income over the set amount is not taxed. in 2019, the maximum amount of taxable money is $132,900.