Each winter, CBO issues a report about the accuracy of our budget projections for the most recent fiscal year compared with the estimates we made before that year began. In that analysis, we remove the effects of legislation enacted during the year and make other adjustments to focus on how accurate the projections were. Compared with our projections for 2023 made in May 2022 (after those adjustments), actual outlays were underestimated by $564 billion (9 percent), and revenues were overestimated by $477 billion (11 percent).
Our underestimate of the 2023 deficit in May 2022 was unusually large, equaling 3.9 percent of gross domestic product (GDP). From 1985 to 2022, for the first fiscal year in our projections, our average absolute error (that is, the average of the errors without regard to whether they are overestimates or underestimates) was 1.1 percent of GDP. During that period, we overestimated the deficit two-thirds of the time, and we underestimated it one-third of the time, as we did last year.
