Spending on outsourced worker services makes up the largest dollar chunk of U.S. government contracting, according to a March 11 Congressional Budget Office analysis for the House Budget Committee, but the agency can't determine how many jobs it funds.

Spending for professional, administrative and management services from the private sector grew the most in real dollas between 2000 and 2012, says CBO in a letter to Maryland Rep. Chris Van Hollen, ranking committee Democrat, who had requested information on the "size and cost of the federal government's contracted workforce."

Of the $500 billion that federal agencies spent for contracted products and services in 2012, the largest component—$94.7 bllion—was for professional, administrative and management services, says CBO. That figure was up 146% from the spending total in 2000.

Agencies spent the second largest amount on "facility-related" services and construction in 2012, $79.1 billion, up 26% from 2000, says the analysis.

According to the CBO data, spending for engineering and technical expertise was the highest among all services categories—accounting for $17.4 billion in 2012. The government spent more on fixed-wing aircraft and liquid propellants, says CBO.

The analysis reports that spending on contracted worker services among non-defense agencies rose a whopping 173% during the 200-2012 decade, from $14.8 billion to $40.4 billion. The U. S. Defense Dept. spent $54.3 billion on such worker services in 2012, up 129% from $23.8 billion spent in 2000, says the CBO analysis.

CBO says its analysis is taken from the Federal Procurement Data System-Next Generation, known as FPDS, which it described as the only source for comprehensive federal contract spending data.

But CBO also cautions that its data accuracy has been questioned and that neither the FPDS database, nor any others, "report the size of the total labor force funded by federal contracts."

CBO notes that DOD has recently begun collecting data on "full-time equivalent" positions funded by some of its services contracts, but it excludes facility-related services and information about subcontracts.

According to CBO, however, the "accuracy and completeness [of the new DOD database] are unknown," and it also does not allow the budget office to compare task performance costs between federal and contracted workers.