but it was Reagan who signed the first tax on social security. Quoting from
the Social Security Administration's official site: Q3. Which political party started taxing Social Security annuities?
A3. The taxation of Social Security began in 1984 following passage of a set of Amendments in 1983, which were signed into law by President Reagan in April 1983. These amendments passed the Congress in 1983 on an overwhelmingly bi-partisan vote.
The basic rule put in place was that up to 50% of Social Security benefits could be added to taxable income, if the taxpayer's total income exceeded certain thresholds.
The taxation of benefits was a proposal which came from the Greenspan Commission appointed by President Reagan and chaired by Alan Greenspan, who is presently serving as Chairman of the Federal Reserve.
However, Clinton did sign an increase on the tax for the FY 1994 budget bill. Quoting from the same site:
In 1993, legislation was enacted which had the effect of increasing the tax put in place under the 1983 law. It raised from 50% to 85% the portion of Social Security benefits subject to taxation; but the increased percentage only applied to "higher income" beneficiaries. Beneficiaries of modest incomes might still be subject to the 50% rate, or to no taxation at all, depending on their overall taxable income.
This change in the tax rate was one provision in a massive Omnibus Budget Reconciliation Act (OBRA) passed that year. The OBRA 1993 legislation was deadlocked in the Senate on a tie vote of 50-50 and Vice President Al Gore cast the deciding vote in favor of passage. President Clinton signed the bill into law on August 10, 1993.