Federal income tax is calculated as a percentage of your earnings, and the percentage rises as you earn more

The federal government taxes your income using a system called tax brackets. You do not pay one flat rate on all your money. Instead, your income is divided into chunks, and each chunk is taxed at a different rate. The rates for 2024 range from 10 percent on your lowest earnings to 37 percent on your highest. Most people fall somewhere in the middle.

How much you actually owe depends on three things: how much you earned, whether you have dependents or certain deductions, and your filing status (single, married filing jointly, head of household, and so on). The IRS publishes new tax brackets and standard deductions every year, so the dollar amounts change annually.

Your employer usually withholds federal income tax from each paycheck based on a form you fill out called a W-4. The amount withheld is an estimate. When you file your tax return, you find out whether you paid too much (and get a refund) or too little (and owe more).

Key Takeaways

  • Federal income tax uses brackets: you pay 10 percent on your first chunk of income, then 12 percent on the next chunk, and so on, not 10 percent on everything.
  • Your employer withholds an estimate from each paycheck based on your W-4 form, which you can update if the amount is wrong.
  • The actual tax you owe is calculated when you file your return, and it depends on your income, filing status, and deductions or credits you claim.
  • Tax brackets and standard deductions change every year, so the dollar amounts that trigger each rate are different in 2024 than they were in 2023.
  • Self-employed people pay federal income tax plus self-employment tax (Social Security and Medicare), which is higher than what employees pay.

How tax brackets work: you do not pay one rate on all your income

The easiest way to understand brackets is with an example. In 2024, the first bracket for a single filer is 10 percent on income up to $11,600. The second bracket is 12 percent on income from $11,601 to $47,150. The third is 22 percent on income from $47,151 to $100,525, and so on.

If you earned $50,000 as a single person in 2024, you would not pay 12 percent on all $50,000. Instead, you would pay 10 percent on the first $11,600, then 12 percent on the next $35,550 (from $11,601 to $47,150), then 22 percent on the remaining $2,850 (from $47,151 to $50,000). Your effective tax rate — the percentage you actually pay on your total income — would be lower than your highest bracket rate.

The IRS publishes the exact bracket amounts for each filing status every January. Single filers, married couples filing jointly, heads of household, and married people filing separately each have different brackets. The brackets are adjusted slightly each year for inflation.

Standard deductions and how they lower your tax bill

Before the IRS calculates your tax, you subtract a standard deduction from your income. This is a set dollar amount that depends on your filing status and age. For 2024, the standard deduction is $14,600 for single filers, $29,200 for married couples filing jointly, and $21,900 for heads of household. If you are 65 or older, you get an extra deduction.

The standard deduction is subtracted from your total income to get your taxable income — the amount the IRS actually taxes. If you earned $50,000 and are single, your taxable income would be $50,000 minus $14,600, which is $35,400. Your tax is calculated on $35,400, not $50,000.

Some people instead itemize deductions — they add up specific expenses like mortgage interest, property taxes, or charitable donations and subtract that total instead of the standard deduction. You choose whichever is larger. Most people use the standard deduction because it is simpler and often larger.

Tax credits that reduce what you owe directly

A tax credit is different from a deduction. A deduction lowers your taxable income. A credit directly reduces the tax you owe, dollar for dollar. If you owe $3,000 in federal income tax and you have a $500 credit, you now owe $2,500.

Common credits include the Earned Income Tax Credit (EITC) for lower-income workers, the Child Tax Credit for parents, and the American Opportunity Credit for students paying college tuition. Some credits are refundable, which means if the credit is larger than the tax you owe, the IRS sends you the difference. Others are non-refundable and can only reduce your tax to zero.

You claim credits when you file your tax return. The IRS does not automatically know you may have access to for them, so you have to report them yourself or use tax software that asks the right questions.

How withholding works and why your refund or bill exists

When you start a job, you fill out a W-4 form that tells your employer how much federal income tax to withhold from each paycheck. You estimate how much tax you will owe for the year, and your employer deducts that amount in installments. The goal is to withhold roughly what you will actually owe, so you break even when you file.

In reality, most people either withhold too much or too little. If you withheld too much, you get a refund when you file your return. If you withheld too little, you owe money. You can update your W-4 at any time during the year if you realize the withholding is wrong — for example, if you got a raise, got married, or had a child.

Self-employed people do not have an employer to withhold for them. Instead, they pay estimated tax four times a year (quarterly) by sending the IRS a check or making an electronic payment. The amounts are based on how much profit they expect to make.

Self-employment tax: an extra layer for people who work for themselves

If you are self-employed, you pay federal income tax like everyone else, but you also pay self-employment tax, which funds Social Security and Medicare. Employees have this deducted from their paychecks (you see it labeled as Social Security and Medicare tax), and their employer matches it. Self-employed people pay both the employee and employer portions themselves.

Self-employment tax is 15.3 percent of your net profit: 12.4 percent for Social Security (up to a cap that changes yearly) and 2.9 percent for Medicare. You calculate it on Schedule SE and include it with your income tax return. You can deduct half of what you pay as a business expense, which lowers your taxable income slightly.

Self-employed people also have the option to deduct business expenses — supplies, equipment, a home office, vehicle mileage, and so on — which lowers their taxable income. This is one reason self-employed people often owe less federal income tax than their gross revenue might suggest.

Filing your return and settling what you actually owe

You file your federal income tax return once a year, usually by April 15. You report all income you earned (from W-2 forms your employers send, 1099 forms for freelance or investment income, and so on), claim any deductions or credits you are may have access to to, and calculate your final tax. The IRS compares this to what you already paid through withholding or estimated payments.

If you paid more than you owe, you get a refund. If you paid less, you owe the difference. You can file on paper or electronically. Many people use tax software (like TurboTax or TaxAct) or hire a tax professional to prepare their return.

The important date to file is April 15 each year, but you can request an extension to October 15 if you need more time. An extension gives you more time to file, but it does not extend the important date to pay — if you owe money, you should pay by April 15 to avoid penalties and interest.

Frequently Asked Questions

What is the difference between federal income tax and other taxes I pay?

Federal income tax goes to the IRS and funds the federal government. You also pay state income tax (in most states), local income tax (in some cities), Social Security and Medicare tax (if you are employed), and sales tax or property tax. Each is separate and calculated differently.

Why do I get a refund if I paid too much in withholding?

Your employer withholds an estimate based on your W-4. If your actual tax is lower than what was withheld — because you had a deduction, a credit, or a life change you did not report — the IRS refunds the overpayment. You can adjust your W-4 to reduce future withholding if this happens every year.

Do I have to file a return if I did not earn much money?

You must file if your income exceeds the standard deduction for your filing status. For 2024, that is $14,600 for single filers. If you earned less and had no tax withheld, you do not have to file, but you might want to if you paid taxes and are owed a refund.

Can I change my W-4 in the middle of the year?

Yes. You can submit a new W-4 to your employer at any time. If you realize you are withholding too much or too little, updating it will adjust your future paychecks. Changes take effect on the next pay period.

What happens if I do not pay my federal income tax?

The IRS charges penalties and interest on unpaid tax. If you cannot pay by April 15, you can request a payment plan (installment agreement) or ask for a temporary delay (currently not collectible status). Contact the IRS directly or work with a tax professional to set this up.