Under current law, the federal budget is on an unsustainable path—meaning that federal debt will continue to grow much faster than the economy over the long run. Although great uncertainty surrounds longterm fiscal projections, rising costs for health care and the aging of the U.S. population will cause federal spending to increase rapidly under any plausible scenario for current law. Unless revenues increase just as rapidly, the rise in spending will produce growing budget deficits and accumulating debt. Keeping deficits and debt from reaching levels that would cause substantial harm to the economy would require increasing revenues significantly
as a percentage of gross domestic product (GDP), decreasing projected spending
sharply, or some combination of the two.
* * *
CBO’s long-term budget projections raise fundamental questions about economic sustainability. If outlays grew as projected and revenues did not rise at a corresponding rate, annual deficits would climb and federal debt would grow significantly. Large budget deficits would reduce national saving, leading to more borrowing from abroad and less domestic investment, which in turn would depress income growth in the United States. Over time,the accumulation of debt would seriously harm the economy. Alternatively, if spending grew as projected and taxes were raised in tandem, tax rates would have to reach levels never seen in the United States. High tax rates would slow the growth of the economy, making the spending burden harder to bear. Policymakers could mitigate the economic damage from rapidly rising debt by putting the nation on a sustainable fiscal course, which would require some combination of lower spending and higher revenues than the amounts now projected. Making such changes sooner rather than later would lessen the risks that current fiscal policy poses to the economy.
From the June 2009 summary of the Long Term Budget Outlook, issued by the Congressional Budget Office.