Where Federal Revenue Comes From
The federal government collects revenue through several mechanisms. Individual income taxes are the largest source, generating roughly 50% of total federal revenue. Payroll taxes — collected to fund Social Security and Medicare — contribute about 36%. Corporate income taxes provide around 10%. Excise taxes, estate taxes, and other sources make up the remainder.
Total federal revenue in recent years has ranged from $4.4 trillion to $5 trillion annually. Revenue fluctuates with economic conditions — recessions reduce income tax and payroll tax collections while economic booms increase them. Tax policy changes enacted by Congress also directly affect revenue levels. The 2017 Tax Cuts and Jobs Act reduced corporate tax rates and modified individual income tax brackets, decreasing revenue relative to what the Congressional Budget Office had previously projected.
Mandatory vs. Discretionary Spending
Mandatory spending is governed by eligibility rules written into law. Anyone who meets the statutory criteria for Social Security, Medicare, or Medicaid receives the benefit automatically — Congress does not need to appropriate funds each year for each recipient. Mandatory spending grows automatically when more people become eligible (through aging populations, for instance) or when benefit levels increase with inflation.
Discretionary spending requires Congress to pass appropriations bills each year to authorize and fund it. The 12 annual appropriations bills cover defense, education, transportation, housing, environmental protection, scientific research, and most other government functions. If Congress fails to pass appropriations bills — or a continuing resolution to extend previous funding — affected agencies shut down.
The political significance of this distinction is enormous. Most of the budget fights in Congress focus on discretionary spending, which is only about one-third of total spending. The larger mandatory programs are harder to change because they involve direct benefits to tens of millions of voters who reliably show up to protect those programs. Politicians who propose cutting Social Security or Medicare face severe electoral consequences.
The National Debt and Interest Costs
The national debt has grown dramatically in recent decades. It crossed $10 trillion during the 2008 financial crisis, $20 trillion in 2017, $30 trillion in 2022, and exceeds $36 trillion in 2026. The debt is financed by selling Treasury bonds, notes, and bills to domestic and foreign investors. The Federal Reserve also holds a significant portion.
Interest on the debt is the fastest-growing category in the federal budget. As the total debt has grown and as interest rates have risen from the near-zero levels of the 2010s, annual interest payments have surged. Annual interest now exceeds the entire defense budget — a striking indicator of how much of the government's revenue is committed to servicing past borrowing rather than funding current services.
How the Budget Process Works
The formal budget process begins when the president submits a budget proposal to Congress in early February. The proposal is not legally binding — it is the administration's statement of priorities. Congress then develops its own budget resolution, which sets overall spending and revenue targets. The House and Senate Budget Committees develop these resolutions, which are subject to full chamber votes.
The budget resolution provides the framework for 12 annual appropriations bills — one for each major area of government. Appropriations Committees in each chamber draft and pass their versions of these bills, which must then be reconciled between the chambers in conference. Both chambers must pass identical final bills before the president signs them into law.
Congress has not passed all 12 appropriations bills on time in more than two decades. The government now operates primarily on continuing resolutions — stopgap funding legislation that extends prior year funding levels — while negotiations continue, often throughout the fiscal year. Government shutdowns occur when continuing resolutions expire without replacement.
Frequently Asked Questions
How much does the US government spend each year?
Approximately $6.5 to $7 trillion annually in recent fiscal years. Mandatory spending (Social Security, Medicare, Medicaid, interest) accounts for roughly 65%. Discretionary spending is the remaining 35%.
What is the national debt and how big is it?
The cumulative total of all annual deficits. As of 2026, the national debt exceeds $36 trillion, consisting of debt held by the public and intragovernmental debt.
What is the difference between the debt ceiling and the budget deficit?
The deficit is the annual gap between spending and revenue. The national debt is all past deficits accumulated. The debt ceiling is a statutory limit on Treasury borrowing to pay obligations Congress already approved.
What is discretionary spending?
The portion of the budget Congress appropriates annually — defense, education, transportation, and other non-entitlement programs. Approximately one-third of total federal spending.
What happens if Congress doesn't pass a budget?
Agencies funded by unpassed appropriations bills shut down non-essential functions. A continuing resolution extends prior-year funding while negotiations continue. Shutdowns occur when CR funding lapses without replacement.