The Congressional Budget Office just published its updated budget projections.

"If the current laws that govern federal taxes and spending do not change, the budget deficit will shrink this year to $642 billion, the Congressional Budget Office (CBO) estimates, the smallest shortfall since 2008," they wrote.

This is way down from an estimate of $845 billion in February.

"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."

Here's an excerpt from the CBO's discussion of what changed since the February projection:

The decline in the projected deficit for 2013 stems largely from a boost in estimated revenues as well as from expected payments to the Treasury by Fannie Mae and Freddie Mac. The changes in CBO’s baseline for the 2014–2023 period result mainly from lower projections of outlays (primarily for Social Security, Medicare, and Medicaid). As a result of those changes, CBO now projects that, under current law, debt held by the public will total 74 percent of GDP in 2023, down from the 77 percent the agency projected in February.

Here's a summary of the CBO's long-term budget projections: