If the current laws that govern federal taxes and spending do not change, the budget deficit will shrink this year to $642 billion, CBO estimates, the smallest shortfall since 2008. Relative to the size of the economy, the deficit this year—at 4.0 percent of gross domestic product (GDP)—will be less than half as large as the shortfall in 2009, which was 10.1 percent of GDP.

Because revenues, under current law, are projected to rise more rapidly than spending in the next two years, deficits in CBO’s baseline projections continue to shrink, falling to 2.1 percent of GDP by 2015. However, budget shortfalls are projected to increase later in the coming decade, reaching 3.5 percent of GDP in 2023, because of the pressures of an aging population, rising health care costs, an expansion of federal subsidies for health insurance, and growing interest payments on federal debt. By comparison, the deficit averaged 3.1 percent of GDP over the past 40 years and 2.4 percent in the 40 years before fiscal year 2008, when the most recent recession began. During the next 10 years, both revenues and outlays are projected to be above their 40-year averages as a percentage of GDP (see figure below).

For the 2014–2023 period, deficits in CBO’s baseline projections total $6.3 trillion. With such deficits, federal debt held by the public is projected to remain above 70 percent of GDP—far higher than the 39 percent average seen over the past four decades. (As recently as the end of 2007, federal debt equaled 36 percent of GDP.) Under current law, the debt is projected to decline from about 76 percent of GDP in 2014 to slightly below 71 percent in 2018 but then to start rising again; by 2023, if current laws remain in place, debt will equal 74 percent of GDP and continue to be on an upward path (see figure below).

Such high and rising debt later in the coming decade would have serious negative consequences: When interest rates return to higher (more typical) levels, federal spending on interest payments would increase substantially. Moreover, because federal borrowing reduces national saving, over time the capital stock would be smaller and total wages would be lower than they would be if the debt was reduced. In addition, lawmakers would have less flexibility than they would have if debt levels were lower to use tax and spending policy to respond to unexpected challenges. Finally, a large debt increases the risk of a fiscal crisis, during which investors would lose so much confidence in the government’s ability to manage its budget that the government would be unable to borrow at affordable rates.

CBO’s estimate of the deficit for this year is about $200 billion below the estimate that it produced in February 2013, mostly as a result of higher-than-expected revenues and an increase in payments to the Treasury by Fannie Mae and Freddie Mac. For the 2014–2023 period, CBO now projects a cumulative deficit that is $618 billion less than it projected in February. That reduction results mostly from lower projections of spending for Social Security, Medicare, Medicaid, and interest on the public debt.