In 2011, Obama signed The Temporary Payroll Tax Cut Continuation Act of 2011, which temporarily extended the payroll tax cut of 2% and the Social Security tax withholding rate reduction from 6.2% to 4.2% through February 29, 2012.
The new payroll tax rate was to be implemented by employers no later than January 31, 2012. If employers over-withheld any Social Security during January, they needed to make an offsetting adjustment to employees’ pay by no later than March 31, 2012.
Source: CNN
