The main purpose of taxation is to give the government the money it needs to operate, but that answer is only the surface of it. Taxes serve four connected purposes: they fund public goods and services, redistribute resources to reduce economic inequality, stabilize the broader economy, and steer individual and business behavior toward outcomes society values. Congress’s authority to collect taxes for these ends comes from Article I, Section 8 of the U.S. Constitution, which empowers it to lay and collect taxes to pay debts and provide for the common defense and general welfare.1Legal Information Institute (LII) / Cornell Law School. Taxing Power
Paying for Public Goods and Services
The most visible reason taxes exist is to pay for things everyone uses but no private company would supply at a profit. National defense, federal courts, interstate highways, and public health infrastructure share two features: you cannot easily keep people from using them, and one person’s use does not diminish another’s. Without tax funding, these public goods would be underproduced, and people who benefited without paying would ride free on the contributions of others.
The dollars involved are large. The Department of Defense alone requested $849.8 billion for fiscal year 2025 to cover personnel, equipment, research, and operations.2U.S. Department of War. Department of Defense Releases the Presidents Fiscal Year 2025 Defense Budget The federal gasoline tax of 18.4 cents per gallon flows into the Highway Trust Fund and keeps interstate roads and bridges in service. Public schools run largely on local property taxes, which vary widely from one district to the next.
Social Insurance
A substantial share of federal revenue does not come from income tax at all. Payroll taxes are dedicated specifically to Social Security and Medicare. For 2026, employees and employers each pay 6.2 percent of wages toward Social Security on earnings up to $184,500, plus 1.45 percent toward Medicare on all wages with no cap.3Social Security Administration. 2026 Cost-of-Living Adjustment (COLA) Fact Sheet Self-employed workers pay both halves, a combined 15.3 percent.4Social Security Administration. If You Are Self-Employed Higher earners pay an extra 0.9 percent Medicare tax on wages above $200,000, or $250,000 for married couples filing jointly.5Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates These dedicated contributions fund retirement, disability, and senior health coverage — programs that would be hard to sustain if participation were voluntary.
Redistributing Resources
The federal income tax is progressive. Rates climb from 10 percent to 37 percent as income rises through seven brackets, so higher earners pay a larger share of each additional dollar. For 2026, a single filer does not reach the top 37 percent bracket until taxable income exceeds $640,600, and married couples filing jointly reach it at $768,700.6Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026, Including Amendments From the One, Big, Beautiful Bill The revenue collected at those graduated rates supports programs that provide a basic standard of living for lower-income households, including the Supplemental Nutrition Assistance Program and the Housing Choice Voucher Program.
The tax code also puts money directly into the hands of working families. The Earned Income Tax Credit reduces the tax bill of low-to-moderate-income workers and often produces a refund larger than the tax owed. For tax year 2026, the maximum EITC reaches $8,231 for families with three or more qualifying children. Unemployment insurance benefits, funded through employer-paid taxes under the Federal Unemployment Tax Act, replace part of a worker’s wages after a layoff.7Office of the Law Revision Counsel. 26 USC Chapter 23 – Federal Unemployment Tax Act Together, these tools shift resources from higher earners toward households that need help meeting basic needs.
The federal estate tax targets the upper end of the wealth distribution. For 2026, estates worth $15,000,000 or less per individual owe nothing, and amounts above that threshold face a top rate of 40 percent.8Internal Revenue Service. Whats New – Estate and Gift Tax The tax reaches only the wealthiest estates but limits how much untaxed wealth passes from one generation to the next.
Stabilizing the Economy
Tax policy is one of the levers Congress uses to manage the economy as a whole. When inflation runs hot, holding taxes steady or raising them pulls money out of circulation and can slow rising prices. When growth stalls, cutting taxes leaves more money with consumers and businesses and encourages spending and investment.
The Tax Cuts and Jobs Act of 2017 is the clearest recent example. It lowered the top individual rate from 39.6 percent to 37 percent and replaced the graduated corporate tax structure, which topped out at 35 percent, with a flat 21 percent corporate rate.9Internal Revenue Service. Tax Cuts and Jobs Act – A Comparison for Businesses The seven-bracket individual structure remains in place for 2026, with the thresholds adjusted upward for inflation each year. Those annual adjustments prevent rising prices alone from pushing taxpayers into higher effective tax burdens, a problem known as bracket creep.
Shaping Behavior
Taxes can also make certain activities more expensive and others cheaper. Economists call taxes on harmful activities Pigouvian taxes because they force the price of a product to reflect the wider costs it imposes on public health or the environment.
The federal excise tax on a standard pack of 20 cigarettes is $1.01, meant to discourage smoking and offset the healthcare costs it creates.10Office of the Law Revision Counsel. 26 USC 5701 – Rate of Tax State taxes stack on top, and combined rates push the total well above $5.00 per pack in some places. Comparable excise taxes apply to alcohol and to fuel-inefficient vehicles.
Incentives run the other direction too. Homeowners who itemize can deduct the interest paid on up to $750,000 of qualified mortgage debt, or $375,000 if married filing separately, which lowers the after-tax cost of owning a home.11Internal Revenue Service. Publication 936 (2025), Home Mortgage Interest Deduction The Residential Clean Energy Credit offers 30 percent back on solar panels and other qualifying clean energy equipment.12Office of the Law Revision Counsel. 26 USC 25D – Residential Clean Energy Credit For businesses, the research and development credit under Section 41 of the Internal Revenue Code equals 20 percent of qualified research spending above a base amount, encouraging companies to invest more in new products and processes.13Office of the Law Revision Counsel. 26 USC 41 – Credit for Increasing Research Activities Each of these provisions is the tax code steering an everyday choice — what you put on your roof, how much a company spends on R&D, whether you buy a house.
Why Compliance Backs All of It
None of these purposes work if the money is not actually collected. Filing a return late without a valid extension triggers a penalty of 5 percent of the unpaid tax per month, up to 25 percent, and returns more than 60 days late carry a minimum penalty of $435 or 100 percent of the tax owed, whichever is less.14Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax Intentional tax evasion is a felony under 26 U.S.C. § 7201, punishable by up to five years in prison and fines of up to $100,000 for individuals or $500,000 for corporations.15Office of the Law Revision Counsel. 26 USC 7201 – Attempt to Evade or Defeat Tax Those penalties exist because every purpose taxation serves — the roads, the safety net, the economic levers, the incentives — depends on the obligation being enforceable.