The amount that one pays in payroll taxes throughout one's working career is indirectly tied to the social security benefits annuity that one receives as a retiree. Some folks claim that the payroll tax is not a tax because its collection is tied to a benefit. The United States Supreme Court decided in Flemming v. Nestor (1960) that no one has an accrued property right to benefits from Social Security.
In this 1960 Supreme Court decision Nestor's denial of benefits was upheld even though he had contributed to the program for 19 years and was already receiving benefits. Under a 1954 law, Social Security benefits were denied to persons deported for, among other things, having been a member of the Communist party. Accordingly, Mr. Nestor's benefits were terminated. He appealed the termination arguing, among other claims, that promised Social Security benefits were a contract and that Congress could not renege on that contract. In its ruling, the Court rejected this argument and established the principle that entitlement to Social Security benefits is not a contractual right.
And they have to buy a supplement, too.