Baseline Budget Projections. The purpose of CBO's budget projections is to give the Congress a baseline for measuring the effects of proposed changes in tax and spending laws. The projections start with the Congress's most recent budgetary decisions and show what would happen to the federal budget if no new policy decisions were made over the projection period. The budget committees use the projections to develop their annual budget resolutions and directives to other committees. CBO uses them to produce cost estimates for proposed legislation and in scorekeeping tabulations.
For revenues and entitlement programs, such as Social Security or Medicare, the baseline projections generally assume that current laws will continue without change. For discretionary spending, which is controlled by annual appropriation bills, CBO bases its projections on the most recent appropriations and the statutory limits on future appropriations. For fiscal years 1998 through 2002, the Balanced Budget Act of 1997 set limits on discretionary spending, extending the limits first put in place by the Budget Enforcement Act of 1990.
