• Declining revenues are driving future deficits. The fact is that rapidly increasing spending will cause 100% of rising long-term deficits. Over the past 50 years, tax revenues have deviated little from their 18% of gross domestic product (GDP) average. Despite a temporary recession-induced dip, CBO projects that even if all Bush tax cuts are extended and the AMT is patched, tax revenues will rebound to 18.2% of GDP by 2020—slightly above the historical average. They will continue growing afterwards.
Spending—which has averaged 20.3% of GDP over the past 50 years—won't remain as stable. Using the budget baseline deficit of $13 trillion for the next decade as described above, CBO figures show spending surging to a peacetime record 26.5% of GDP by 2020 and also rising steeply thereafter.
Putting this together, the budget deficit, historically 2.3% of GDP, is projected to leap to 8.3% of GDP by 2020 under current policies. This will result from Washington taxing at 0.2% of GDP above the historical average but spending 6.2% above its historical average.
Entitlements and other obligations are driving the deficits. Specifically, Social Security, Medicare, Medicaid and net interest costs are projected to rise by 5.4% of GDP between 2008 and 2020. The Bush tax cuts are a convenient scapegoat for past and future budget woes. But it is the dramatic upward arc of federal spending that is the root of the problem.