President Regan instated taxes on SS. There were none prior.
Congress imposed it. Reagan signed it into law.
Biden was a driving force behind it.
When it came to the budget and taxes, that was all Dems.
For that 1983 SS bill, tons of GOP went with the "no vote" option.
The Senate vote was 58-14. (At least 12 GOP crossed, and about 30 went "no vote"
The House vote was 243-102. (About 60 GOP went "no vote". The media called this "strong bipartisan support".)
And...
The 1993 Omnibus Budget Reconciliation Act increased the proportion of Social Security benefits subject to taxation, raising the limit to 85% for higher earners. The 1993 Congress was 257-177, Dem. The Senate was 57-43, Dem. Clinton was President.
It barely passed... In the House, it was 218-216, with 42 Dems voting against it. All 174 GOP votes were "nay". Vice President Al Gore broke the 50-50 tie in the Senate, despite 7 Dems voting against it. Again, every GOP voted "nay'.