Where Does Income Tax Go? Federal Buckets and State Spending

Federal income tax goes into the U.S. Treasury’s general fund, where Congress can spend it on almost anything it appropriates. In practice, most of it pays for Medicare, Medicaid, defense, the rest of the annually funded government, and a fast-growing interest bill on the national debt. Social Security, despite being the single largest federal program, runs mostly on a separate payroll tax rather than on the income tax line of your W-2. For fiscal year 2026, individual income taxes are projected to raise about $2.75 trillion, roughly half of the $5.6 trillion in total federal receipts.¹

Income Tax and Payroll Tax Are Not the Same Pot

Your paycheck shows two very different federal deductions, and they end up in different places. Income tax withholding flows into the Treasury’s general fund, which finances the government as a whole. FICA deductions are earmarked: the Social Security portion goes into the Social Security trust funds, and the Medicare portion into the Medicare trust fund. When people say “my taxes pay for Social Security,” what actually pays for Social Security is the 6.2% payroll tax on earnings up to $184,500 in 2026, matched by another 6.2% from the employer.²

That distinction matters for the rest of this answer. Everything below about where “your income tax” goes is really about how Congress spends the general fund. Payroll tax dollars follow a separate track into the trust funds that pay retirement, disability, and hospital-insurance benefits.

The Three Buckets: Mandatory, Discretionary, and Interest

Total federal spending for fiscal year 2026 is projected at about $7.4 trillion, or 23.3% of the U.S. economy. That spending falls into three categories:¹

Mandatory programs written into permanent law: about $4.5 trillion
Discretionary programs Congress funds each year through appropriations: about $1.9 trillion
Net interest on the national debt: more than $1 trillion

Because receipts of $5.6 trillion fall well short of $7.4 trillion in spending, the government borrows to cover the gap — a projected $1.9 trillion deficit, or 5.8% of GDP.¹ Every deficit dollar adds to the debt and, in turn, to next year’s interest bill.

Mandatory Spending: Health Care Dominates

Mandatory spending consumes about 61% of the federal budget. These programs run on autopilot: anyone who meets the eligibility rules receives benefits, and Congress doesn’t vote on the total each year. The three biggest for fiscal year 2026 are:¹

Social Security: about $1.7 trillion for retirement, survivor, and disability benefits
Medicare: $1.1 trillion for health coverage of people 65 and older and certain people with disabilities
Medicaid: $708 billion in federal spending for health care for low-income individuals and families

Here is where income tax dollars actually reach these programs. Social Security is funded primarily by its dedicated payroll tax, so income tax revenue only backstops it indirectly if the trust fund runs short. Medicare is split: Part A (hospital, skilled nursing, hospice) is largely paid for by the Medicare payroll tax, while Part B (doctor visits, outpatient care, preventive services) and Part D (prescription drugs) are funded primarily by the general fund plus enrollee premiums.³ So a real portion of your income tax goes to Medicare, just not to the hospital-insurance half of it.

Medicaid is a joint federal-state program. The federal government pays at least 50% of each state’s Medicaid costs, with poorer states receiving a higher federal match. That federal share comes out of the general fund, meaning income tax revenue. Because eligibility for all three programs is set in law, spending grows automatically as the population ages and health care costs rise.

Discretionary Spending: Defense and Everything Else

Discretionary spending totals about $1.9 trillion for fiscal year 2026, split almost evenly between defense and nondefense. Congress controls this spending through annual appropriations bills; if those bills don’t pass, the affected agencies shut down.¹

Defense accounts for $885 billion, covering military pay, equipment, operations, and maintenance of bases worldwide. Nondefense discretionary spending totals $996 billion and covers most of what people picture when they think of “the federal government”:¹

Education grants to school districts and federal student loan administration
Highway maintenance, aviation safety, and transit
Federal law enforcement, prosecution, and the federal prison system
Scientific research through the National Institutes of Health, NASA, and similar agencies
Veterans’ health care and benefits administration
Diplomatic operations and foreign aid

Discretionary spending has been shrinking as a share of the economy for decades. In the 1960s it exceeded 10% of GDP. For 2026 it’s projected at 5.9%. Mandatory programs and interest keep growing, squeezing the portion of the budget Congress actively debates.

Interest on the National Debt

The federal government borrows by selling Treasury bills, notes, and bonds, all backed by the full faith and credit of the United States.⁴ Net interest payments for fiscal year 2026 are projected to exceed $1 trillion, or about 3.3% of GDP. That’s more than the entire defense budget.¹

Federal debt held by the public is projected to reach 101% of GDP in 2026, and interest costs are projected to climb to 4.6% of GDP by 2036 as both the debt balance and interest rates remain elevated.¹ Every dollar of income tax spent on interest is a dollar unavailable for programs or tax relief, and this line has become one of the fastest-growing pieces of the budget.

Spending That Happens by Not Collecting

Some of what your income tax “does” is money the government chooses not to collect in the first place. Tax credits, deductions, and exclusions reduce federal revenue to achieve policy goals without writing a check. The Treasury Department estimates these tax expenditures will cost about $1.7 trillion in forgone revenue for fiscal year 2026, nearly as much as total discretionary spending.⁵

The largest ones include the exclusion of employer-provided health insurance from taxable income, preferential rates on capital gains, the mortgage interest deduction, and retirement account tax benefits. Some credits target lower earners specifically. The child tax credit, for example, is worth up to $2,200 per qualifying child under 17 for 2026, with up to $1,700 refundable, phasing out starting at $200,000 of modified adjusted gross income for single filers and $400,000 for joint filers. These provisions never appear in any appropriations bill, but they shape federal finances as much as direct spending does.

State Income Tax Goes Somewhere Else

State income tax is a separate system from federal income tax, and the money stays in the state. Most states impose their own income tax on top of the federal one, with top marginal rates ranging from roughly 2.5% to over 13%; eight states levy no individual income tax at all. Some states use a flat rate, others use progressive brackets, and a few tax only investment income.

State income tax revenue funds services the federal government generally doesn’t provide directly:

K–12 public education, typically the single largest line in state budgets
State highways, bridges, and local transit
State police, courts, prisons, and emergency services
The state share of Medicaid, mental health services, and other public assistance
Public universities and community colleges

Income taxes and sales taxes each account for roughly a third of total state tax collections nationwide, with the rest coming from corporate taxes, property taxes, excise taxes, and fees. States without an income tax lean more heavily on sales taxes or natural resource revenue. Where you live shapes not just how much state tax you pay, but what that money buys.

1
Congressional Budget Office. The Budget and Economic Outlook: 2026 to 2036
2
Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates
3
Medicare. Parts of Medicare
4
TreasuryDirect. About Treasury Marketable Securities
5
U.S. Department of the Treasury. Tax Expenditure Budget for Fiscal Year 2026