The Constitution gives Congress the power of the purse: no money shall be drawn from the Treasury but in consequence of appropriations made by law. For most of the nation's history, Congress handled spending agency by agency. Today the process runs through a presidential budget request, congressional budget resolutions, appropriations bills, and laws that let much of the budget run on autopilot.
This guide follows the money from revenue to spending, explains the annual budget cycle, and covers the flashpoints, from shutdowns to the debt ceiling, that make budgeting one of the most contentious jobs in Washington.
The Constitution places spending power in Congress, but Presidents have sought more control. The Impoundment Control Act of 1974 limits a President's ability to withhold appropriated funds, a limit tested again in 2025 disputes over frozen grants and proposed rescissions. Earmarks let members direct money to specific projects, and sequestration imposes automatic cuts when budget caps are breached. Supporters of a stronger presidential role cite waste and accountability, while defenders of Congress cite the constitutional power of the purse.
Congress has passed all twelve appropriations bills on time only a handful of times since the modern process began in 1976. Instead it relies on continuing resolutions that extend existing funding, large omnibus packages that combine many bills, and supplemental appropriations for emergencies. When funding lapses without a stopgap, the Antideficiency Act forces a shutdown of nonessential operations. Reconciliation lets Congress pass tax and mandatory spending changes by simple majority in the Senate.
Individual income taxes supply about half of federal revenue, and payroll taxes for Social Security and Medicare supply about a third. Corporate income taxes, tariffs and customs duties, excise taxes, and estate taxes make up most of the rest. The Internal Revenue Service collects most of it and the Treasury Department manages the government's accounts. When revenue falls short of spending, the Treasury borrows by selling securities to the public.
Federal spending falls into three categories. Mandatory spending, set by permanent law, includes Social Security, Medicare, Medicaid, and other benefit programs, and makes up about two-thirds of the total. Discretionary spending, about a quarter, is set each year in appropriations bills and covers defense, veterans' health care, transportation, research, law enforcement, and most agency operations. Net interest on the debt makes up the rest and has grown rapidly as rates and borrowing have risen. More than $1 trillion a year also flows to state and local governments as grants.
The process begins with the President's budget, due on the first Monday in February and prepared by the Office of Management and Budget. Congress is supposed to adopt a budget resolution setting overall spending and revenue targets, though in many years it does not. Authorizing committees create and shape programs, while the Appropriations Committees write twelve annual bills that actually provide the money. The Congressional Budget Office scores every proposal, and the Government Accountability Office audits how money is spent.
The deficit is the gap between spending and revenue in a single year, and the debt is the total accumulated borrowing. Debt held by the public has climbed to roughly the size of the entire economy. The debt ceiling, a statutory limit on federal borrowing, must be raised or suspended periodically to pay bills Congress has already approved, producing recurring standoffs. Economists and lawmakers disagree about how urgent the debt problem is and whether to address it through spending cuts, tax increases, or faster growth.
When appropriations lapse, the consequences are immediate. See what happens in a shutdown and who gets furloughed, or follow budget bills through Congress in how a bill becomes law.