The CBO reports in its new Budget and Economic Outlook, which covers the years from 2014 through 2024:
Federal outlays are expected to increase by 2.6 percent this year, to $3.5 trillion, or 20.5 percent of GDP—their average percentage over the past 40 years. CBO projects that under current law, outlays will grow faster than the economy during the next decade and will equal 22.4 percent of GDP in 2024. With no changes in the applicable laws, spending for Social Security, Medicare (including offsetting receipts), Medicaid, the Children’s Health Insurance Program, and subsidies for health insurance purchased through exchanges will rise from 9.7 percent of GDP in 2014 to 11.7 percent in 2024, CBO estimates. Net interest payments by the federal government are also projected to grow rapidly, climbing from 1.3 percent of GDP in 2014 to 3.3 percent in 2024, mostly because of the return of interest rates to more typical levels. However, the rest of the government’s noninterest spending—for defense, benefit programs other than those mentioned above, and all other nondefense activities—is projected to drop from 9.4 percent of GDP this year to 7.3 percent in 2024 under current law.
The CBO provides the graph to project federal government budget deficits over the next 10 years: