Government Spending Accountablity Act - Reduces the amount that a federal agency may pay or reimburse for travel costs: (1) in FY2013-FY2014 to 50% of the amount paid or reimbursed by such agency in FY2012, and (2) in FY2015 to 75% of the amount paid or reimbursed in FY2012. Exempts from such reduction: (1) the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF); (2) the Department of Defense (DOD); (3) the Drug Enforcement Administration (DEA); (4) the Federal Air Marshall Service; (5) the Federal Bureau of Investigation (FBI); (6) the U.S. Capitol Police; (7) the U.S. Citizenship and Immigration Service; and (7) the U.S. Secret Service.