No, the Federal Government does not figure out anything and the employers are not refunded the "excess" tax that the employers paid. The employer's share of the Social Security tax is on the activity of the employer in paying the wages, and that activity occurred regardless of any other employment of the wage earner elsewhere.

No, the Federal Government does not figure out anything and the employers are not refunded the "excess" tax that the employers paid. The employer's share of the Social Security tax is on the activity of the employer in paying the wages, and that activity occurred regardless of any other employment of the wage earner elsewhere.

If an employee's gross income from an employer exceeds the Social Security wage base for that year, neither the employee nor the employer has to pay Social Security tax on the excess. Medicare taxes continue to be paid by both on the income above the Social Security wage base since there is no wage base for Medicare taxes. In a new twist, starting in 2013, additional Medicare taxes are withheld on the wages of employees making more than $200K but this is a tax on employees only; there is no corresponding employer's share of the extra Medicare taxes.