Individual Income Tax

What is an Individual Income Tax?

An individual income tax (or personal income tax) is levied on the wages, salaries, investments, or other forms of income an individual or household earns. The U.S. imposes a progressive income tax where rates increase with income. Individual income taxes are the largest source of tax revenue in the U.S.

How Does the Individual Income Tax Work?

In the United States, individual income taxes are levied at the federal level as well as in most states. Many countries around the world also levy individual income taxes.

The U.S. income tax is progressive, which means that tax rates increase as taxpayer income increases. The U.S. levies income tax rates ranging from 10 percent to 37 percent that kick in at the specific income thresholds outlined below. The income ranges for which these rates apply are called tax brackets. All income that falls within each bracket is taxed at the corresponding rate.

2021 Federal Income Tax Brackets and Rates for Single Filers, Married Couples Filing Jointly, and Heads of Households
Rate For Unmarried Individuals For Married Individuals Filing Joint Returns For Heads of Households
10% $0 to $9,950 $0 to $19,900 $0 to $14,200
12% $9,951 to $40,525 $19,901 to $81,050 $14,201 to $54,200
22% $40,526 to $86,375 $81,051 to $172,750 $54,201 to $86,350
24% $86,376 to $164,925 $172,751 to $329,850 $86,351 to $164,900
32% $164,926 to $209,425 $329,851 to $418,850 $164,901 to $209,400
35% $209,426 to $523,600 $418,851 to $628,300 $209,401 to $523,600
37% $523,601 or more $628,301 or more $523,601 or more

Source: Internal Revenue Service

A graduated-rate structure like the one above, where every dollar of income above each threshold is taxed at a higher rate, results in marginal tax rates, the amount of additional tax paid for every additional dollar earned as income.

Due to various deductions, such as the standard deduction and itemized deductions, and credits, such as the Earned Income Tax Credit (EITC) and Child Tax Credit (CTC), most taxpayers do not pay federal income taxes on all of their income. Many state tax codes also offer similar credits and deductions.

Tax Basics - How Is Tax Liability Calculated, adjusted gross income, average tax rate, child tax credit, earned income tax credit, individual income tax, itemized deduction, marginal tax rate, standard deduction, tax credit, tax deduction, taxable income

The Phase-In and Phaseout of the EITC Earned Income Tax Credit

Which States Levy Individual Income Taxes?

As of 2020, 43 U.S. states also levy individual income taxes. Forty-one tax wage and salary income, while two states—New Hampshire and Tennessee—exclusively tax dividend and interest income. Seven states levy no individual income tax at all.

Of those states taxing wages, nine have single-rate tax structures, often called a “flat tax,” with one rate applying to all taxable income. Conversely, 32 states and the District of Columbia levy graduated-rate, progressive income taxes, with the number of brackets varying widely by state. Hawaii has 12 brackets, the most in the country.

2020 State Individual Income Tax Rates and Brackets, 2020 state individual income taxes, 2020 state income tax rates, 2020 state income tax

States’ approaches to income taxes vary in other details as well. Some states double their single-bracket widths for married filers to avoid a “marriage penalty.” Some states index tax brackets, exemptions, and deductions for inflation; many others do not. Some states tie their standard deductions and personal exemptions to the federal tax code, while others set their own or offer none at all.

Who Pays the Federal Income Tax?

The progressive design of the U.S. income tax code leads to higher-income individuals paying a larger share of income taxes than lower-income individuals.

According to 2017 federal income tax data from the Internal Revenue Service (IRS), the most recent available:

  • The top 50 percent of all taxpayers paid 97 percent of all individual income taxes, while the bottom 50 percent paid the remaining 3 percent.
  • The top 1 percent paid a greater share of individual income taxes (38.5 percent) than the bottom 90 percent combined (29.9 percent).
  • The top 1 percent of taxpayers paid a 26.8 percent average individual income tax rate, which is more than six times higher than taxpayers in the bottom 50 percent (4.0 percent).

The Top 1 Percent of U.S. Earners Pay 25 Percent of All Federal Taxes, federal individual income tax

US progressive tax system, federal income tax data 2020 individual income tax

Between 1950 and 2016, an increasing number of U.S. taxpayers owed zero income taxes after credits and deductions. Despite occasional dips, the trend has been an increase in the percentage of nonpayers, from 28 percent in 1950 to 33.4 percent in 2016. During this period, the minimum percentage of nonpayers was 16 percent in 1969, and the maximum was 41.7 percent in 2009.

Americans zero income tax liability percentage of nonpayers has increased over time, progressive individual income tax code.

Individual Income Taxes Are a Primary Source of Government Revenue

Compared to the OECD average, the United States relies significantly more on individual income taxes than other developed countries. While OECD countries on average raised 23.9 percent of total tax revenue from individual income taxes in 2018, in the U.S., individual income taxes (federal, state, and local) were the primary source of tax revenue at 40.72 percent, a difference of almost 17 percentage points.

Sources of Tax Revenue in the United States, individual income tax

Sources of Tax Revenue in the United States Compared to the OECD Average, 2018 individual income tax

State and localities rely heavily on the individual income tax, which comprised 23.3 percent of total U.S. state and local tax collections in fiscal year 2017, the latest year of data available. The level of reliance on income taxes varies significantly by state.

2020 state individual income tax reliance 2020 state income tax reliance

Was this page helpful to you?


Thank You!

The Tax Foundation works hard to provide insightful tax policy analysis. Our work depends on support from members of the public like you. Would you consider contributing to our work?

Contribute to the Tax Foundation