" DOD is the government's largest purchaser of contractor-provided services. In 2008, Congress required DOD to compile and review an annual inventory of its contracted services to include the number of contractors providing services to DOD and the functions these contractors performed, and in 2011, amended this statute to require DOD to plan to use that inventory to inform certain department-wide decision making processes. The National Defense Authorization Act for Fiscal Year 2014 mandated GAO to report on the required reviews and plans to use these inventories. For this report, GAO assessed the extent to which DOD components (1) reviewed contracts and activities in the fiscal year 2012 inventory of contracted services and (2) developed plans to use the inventory for decision-making. GAO reviewed relevant laws and guidance, reviewed component certification letters from 32 components, and interviewed DOD acquisition, manpower, programming, and budgeting officials. "