The Congressional Budget Office was set up by Congress to give specialist advice on costing and budgetary issues. It reviews legislatives proposals and the budget put forward by the Executive Branch. As a former elected official myself, I know how important it is to challenge the assumptions behind claims about the costs and savings of proposed actions.
The agency is composed primarily of economists and public policy analysts. About three-quarters of its professional staff hold advanced degrees, mostly in economics or public policy.
A fact sheet on the CBO is available here.
CBO Reports are published on its website http://www.cbo.gov/
The Analysis of the President's proposed budget for FY 2012 can be accessed here.