Troops who were called on to serve their country in the wake of Sept. 11, 2001 are eligible for back pay of $500 for each month of involuntary service. The federal government is now actively contacting 145,000 troops to reward them for their bravery in the months and years following the worst terror attack ever of U.S. soil.

The back pay -- known as Retroactive Stop Loss Special Pay (RSLSP) -- was approved by Congressional act in October 2009. Some 90,000 of the 145,000 who are eligible for RSLSP are believed to be Army veterans. The remainder of those who are eligible are active-duty members split among the branches of the military.

The typical recipient of RSLSP receives $3,700, according to the government. (If the service member is no longer alive, the money will go their beneficiaries.) Some eligibility exceptions do apply. For instance, soldiers who accepted re-enlistment bonuses are ineligible for RSLSP.

In order to claim the money, you must file an application at Defense.gov/StopLoss by Oct. 21, 2010.