Social Security taxes are a flat 12.4% of the first $106,800 of a person's wages, salary or self-employment income. Employers pay half (6.2%) and employees pay half (the other 6.2%). For 2010 only, employers who hire previously unemployed or underemployed workers may be exempt from paying the employer's half of Social Security taxes through the end of 2010.
Qualifying for the Social Security Tax Exemption
An employer can qualify for exemption from paying the employer's half of Social Security taxes by hiring an employee who- begins employment after February 3, 2010, and before January 1, 2011,
- was unemployed or employed for less than 40 hours during the 60-day period ending on the date that employment begins, and
- is not a family member related to the employer or owns more than 50% of the business.
Employers who continue to employ these new hires for at least one full year may become eligible for the New Hire Retention Tax Credit.

