Is severance pay due to a lay off subject to FICA taxes?

In November of 2012 the U.S. Court of Appeals ruled against the IRS by affirming a lower court's decision that severance pay do to a lay off are not subject to FICA taxes. This month we will see if the US Supreme Court will upholds the Appeals court’s ruling. If the Court rules against the IRS, the agency will need to process retroactive refund claims submitted by employers and employees. These claims could reach a total in the billions, and cause the IRS to lose a major source of future revenue.

See http://www.law.cornell.edu/supct/cert/12-1408