From The Congressional Budget Office

Under the Congressional Budget and Impoundment Control Act of 1974, which created CBO, the agency’s primary duty is to provide budget-related information to the Committees on the Budget of the House and Senate. CBO is also required to assist the House and Senate Committees on Appropriations, the House Committee on Ways and Means, the Senate Committee on Finance, other committees, and Members of Congress. The law further requires CBO to prepare several budget projections each year, produce cost estimates of legislation ordered reported by Congressional committees, and publish studies of budgetary issues.