At least theoretically, Social Security isn't a tax at all - it's a mandatory retirement account that the government controls (and raids at will). Sure, if someone dies before they can receive any benefit, it may be a tax (though there are all sorts of rules on spousal benefits for widows/widowers, etc.), but it is not considered ipso facto a tax. And the Medicare/Medicaid portion is just 1.5% of gross income for employees.