At the end of each fiscal year, CBO undertakes a detailed review of actual spending, as reported by the Administration, to assess the quality of its outlay projections.

In March 2016, CBO projected that federal outlays for fiscal year 2017 would total $4.1 trillion—about $65 billion, or 1.6 percent, more than the actual amount reported by OMB. That difference is smaller than the mean absolute error of 2.3 percent for projections made for 1993 to 2016.

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