How Taxes Fund Public Services: The Basics of Government Revenue
Every government service — from roads to courts to public health — requires revenue. Understanding where government money comes from is a prerequisite for evaluating arguments about what it should spend.
Published June 9, 2026Debates about taxation are among the most persistent in democratic politics, and they are often conducted at a level of abstraction that obscures the basic mechanics. Before evaluating arguments about whether taxes are too high or too low, who should pay more or less, or which services are worth the cost, it helps to understand how the revenue system actually works.
The major types of taxes
The federal government derives most of its revenue from three sources. The individual income tax is the largest, accounting for roughly half of federal revenue. It is a progressive tax, meaning the rate increases with income: lower earners pay a lower percentage of their income than higher earners. The payroll tax is the second largest source, funding Social Security and Medicare. Unlike the income tax, it is capped — income above a threshold is not subject to the Social Security portion — making it effectively regressive relative to total income. The corporate income tax is a third source, though its share of federal revenue has declined substantially since the mid-twentieth century.
State governments rely more heavily on sales taxes and state income taxes, with significant variation. Nine states have no income tax at all, funding their governments primarily through sales taxes and other sources. Local governments depend heavily on property taxes, which are assessed on real estate and personal property within the jurisdiction.
What taxes pay for
At the federal level, the largest categories of spending are Social Security, Medicare and Medicaid, defense, and interest on the national debt. These four categories account for the large majority of federal spending. Discretionary programs — education grants, transportation infrastructure, scientific research, and most other federal activities — make up a smaller share and are the subject of the annual budget appropriations process.
At the state level, the largest expenditures are typically Medicaid (jointly funded with the federal government), K-12 education, higher education, and transportation. At the local level, schools and public safety dominate budgets.
How government borrowing fits in
Government revenue and government spending are rarely in balance. When spending exceeds revenue, the government borrows to make up the difference, adding to the national debt. Federal borrowing is done by issuing Treasury bonds, which investors worldwide purchase because they are considered among the safest assets available. The debt carries an annual interest cost that has grown as both the total debt and interest rates have increased.
Arguments about deficit spending involve genuine economic disagreements. Some economists argue that government borrowing during downturns stabilizes the economy and is paid back through growth; others argue that large structural deficits crowd out private investment and burden future generations. These are empirical debates with real uncertainty, not merely ideological ones.
Progressive versus regressive taxation
A progressive tax takes a higher percentage from higher-income individuals. A regressive tax takes a lower percentage from higher earners, even if they pay more in absolute dollars. Sales taxes are typically regressive because lower-income households spend a higher proportion of their income on purchases, while wealthier households save more. The overall tax system — federal, state, and local combined — is less progressive than the federal income tax alone because state and local taxes tend toward regressivity.
Debates about the right balance between progressive and regressive taxation involve both empirical questions (what effects do different structures have on growth, savings, and investment?) and normative ones (what distribution of the tax burden is fair?). Understanding the mechanics is necessary for engaging those debates honestly, but it does not resolve them. The resolution requires value judgments about which reasonable people genuinely disagree.