The federal Social Security tax is 12.4 percent, split evenly between the employee and the employer. Teachers' Retirement System retirement benefits were significantly better than those offered under Social Security. A 1999 study by the General Accounting Office found that adding teachers and other public employers from around the country who are not currently in Social Security would create, at best, a temporary surge in revenue for Social Security. Over the long term, adding teachers to Social Security would only increase the System’s total obligations and deepen the program’s long-term funding problem. Having said this, yes, it's also the case that the federal government cannot force states to participate in Social Security -- at least not directly.

Source: Forbes July 23, 2018 11:03 UTC