Income tax is a tax on the money you earn, collected by the federal government and most states

Income tax is a percentage of your wages, salary, self-employment income, investment gains, and other money you receive that goes to the federal government and, in most states, to your state government as well. The federal government uses this money to fund programs like Social Security, Medicare, defense, and infrastructure. Your state uses its share for schools, roads, and state programs.

The key difference between income tax and other taxes you pay is that income tax is based on what you earn, not what you spend. When you buy a shirt, you pay sales tax on the purchase price. When you own a house, you pay property tax on its value. But income tax is calculated on your actual income — the money that comes into your hands during the year.

The amount you owe depends on how much you earned and which tax bracket you fall into. The federal government uses a progressive system, meaning higher earners pay a higher percentage. This is different from a flat tax (everyone pays the same percentage) or a regressive tax (lower earners pay a higher percentage).

Key Takeaways

  • Income tax is collected by the federal government and by most states, with the rate depending on how much money you earned during the year.
  • The federal government uses a progressive tax system where higher earners pay a higher percentage of their income than lower earners.
  • Income tax is separate from FICA taxes (Social Security and Medicare), which are also withheld from your paycheck but fund different programs.
  • You report your income and calculate what you owe using a tax return, usually Form 1040 for federal taxes and a state form for state taxes.
  • Your employer withholds an estimated amount from each paycheck, but you may owe more or receive a refund when you file your return.

How income tax differs from FICA and other payroll taxes

When you look at your paycheck stub, you see several deductions. FICA taxes — Social Security and Medicare — are separate from income tax, even though they come out of the same paycheck. FICA is a flat percentage (6.2% for Social Security, 1.45% for Medicare if you are an employee), and it funds those specific programs. Income tax is progressive and funds the general operations of government.

This matters because FICA has a wage cap. In 2024, you stop paying Social Security tax after you earn $168,600 in a year. But there is no cap on income tax — you pay it on every dollar you earn. Also, FICA is the same whether you earn $30,000 or $300,000, while income tax rises as your income rises.

Self-employed people pay both the employee and employer portions of FICA (called self-employment tax), which is why their FICA burden is roughly double that of an employee. But the income tax calculation works the same way for self-employed people as for employees — it is based on your total net income for the year.

The difference between ordinary income and capital gains

Not all income is taxed the same way. Ordinary income — wages, salary, tips, interest, and self-employment income — is taxed at your regular tax bracket rate. But capital gains — profit from selling an investment like a stock or rental property — often get a lower tax rate.

If you hold an investment for more than one year before selling it, you pay long-term capital gains tax, which maxes out at 20% federally (compared to ordinary income rates that can reach 37%). If you sell within one year, it is taxed as ordinary income. This is why wealthy people who earn most of their money from investments rather than wages often pay a lower effective tax rate than someone earning the same amount in salary.

Certain types of income are not taxed at all, or are taxed differently. Municipal bond interest, for example, is usually not subject to federal income tax. Roth IRA withdrawals (after age 59½) are not taxed. Understanding which income gets which treatment is important when you file your return.

How tax brackets work and why a higher bracket does not mean you pay more on all your income

The federal government divides income into brackets, and each bracket has a different tax rate. In 2024, for a single filer, income from $0 to roughly $11,600 is taxed at 10%, income from $11,600 to $47,150 is taxed at 12%, and so on, up to 37% on income over $578,100. But this does not mean that if you earn $50,000, you pay 12% on all of it.

Instead, you pay the lower rate on the lower portion and the higher rate only on the portion that falls into that bracket. If you earn $50,000, you pay 10% on the first $11,600 and 12% on the remaining $38,400. Your effective tax rate — the percentage of your total income that goes to taxes — is lower than your marginal rate (the rate on your last dollar earned).

This is why moving into a higher tax bracket does not mean you suddenly owe more money on your entire income. You only pay the higher rate on the income that actually falls into that bracket. Understanding this prevents the common mistake of turning down a raise or bonus because you think it will push you into a higher bracket and cost you money overall.

What gets reported on your tax return and where the numbers come from

Your employer sends you a W-2 form by January 31 each year, showing your wages and the taxes already withheld. If you are self-employed, you track your own income and expenses and report them on Schedule C. If you have investment income, you receive 1099 forms from banks, brokers, and other sources showing interest, dividends, or capital gains.

You use these documents to fill out your federal tax return, usually Form 1040. You add up all your income from all sources, subtract deductions (either the standard deduction or itemized deductions), and calculate what you owe. Your state return works similarly, using a state-specific form.

The IRS already knows much of this information because employers and financial institutions report it to them. When you file, you are confirming those numbers and reporting anything the IRS does not already know about. If your numbers do not match what was reported to the IRS, you may receive a notice asking you to explain the difference.

Why your employer withholds taxes from your paycheck

Withholding is an estimate of the income tax you will owe, taken out of each paycheck throughout the year. Your employer calculates it based on information you provide on Form W-4 — your filing status, number of dependents, and any extra income or deductions you expect.

The goal of withholding is to collect roughly the right amount over the year so that when you file your return, you either owe very little or receive a small refund. If your withholding is too high, you get a refund. If it is too low, you owe money when you file. Neither is a penalty — it is just the government returning overpaid money or you paying what you actually owe.

You can adjust your withholding by filing a new W-4 with your employer. This is useful if your life changes — you get married, have a child, take a second job, or expect a large bonus. Adjusting withholding does not change how much tax you owe overall; it just spreads the payment differently across the year.

State income tax and which states do not have it

Most states collect their own income tax in addition to federal income tax. The rates and brackets vary widely by state. Some states have a flat tax (everyone pays the same percentage), while others use progressive brackets like the federal system. A few states have no income tax at all.

States with no income tax include Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington, and Wyoming. New Hampshire and Tennessee tax only investment income, not wages. If you live in one of these states, you file a federal return but no state return (unless you earned income in another state).

If you moved during the year or worked in multiple states, you may owe income tax to more than one state. Some states offer credits to prevent you from paying tax twice on the same income, but you have to claim them on your return. This is one reason to keep records of where you lived and worked throughout the year.

Frequently Asked Questions

Is income tax the same as payroll tax?

No. Income tax and FICA (payroll tax) are both withheld from your paycheck, but they fund different programs and are calculated differently. FICA is a flat percentage that funds Social Security and Medicare. Income tax is progressive and funds general government operations. You report both on your tax return, but they are separate calculations.

What happens if I do not earn enough to file a tax return?

You are not required to file if your income is below the standard deduction for your filing status. In 2024, that is roughly $14,000 for a single person and $28,000 for a married couple filing jointly. However, if taxes were withheld from your paycheck, you should file to get a refund of that money.

Why do I owe taxes if my employer already withheld money?

Withholding is an estimate based on the information you provide on your W-4. If your actual tax situation is different — you have a second job, investment income, or fewer dependents than you claimed — you may owe more. You can adjust your W-4 to change future withholding, but you still owe what you actually earned.

Can I deduct my expenses from my income before paying tax?

If you are an employee, you generally cannot deduct work expenses anymore. If you are self-employed, you deduct business expenses from your gross income to calculate your net income, which is what you pay tax on. You can also take either the standard deduction or itemize deductions to reduce your taxable income.

What is the difference between a tax refund and a tax credit?

A refund is money the government returns to you because you overpaid through withholding. A credit is a reduction in the tax you owe — some credits are refundable, meaning you get money back even if you owe no tax, while others only reduce what you owe. Credits are generally more valuable than deductions because they reduce your tax dollar-for-dollar.