Over a century ago, fewer than 1% of Americans paid income taxes—but the cost of World War II prompted the federal government to greatly expand the number of people required to pay income taxes.

The US officially adopted an income tax in 1913

The US first levied income taxes during the Civil War, but modern income taxes became an American fixture in 1913. Two years earlier, Congress passed the 16th Amendment to give the government the right to tax individuals' and businesses' income. The US still technically levies the same federal income tax now as it did then—though it's evolved.

On July 1, 1862, the agency now known as the Internal Revenue Service was established and named the Bureau of Internal Revenue

It was created to collect the first-ever US income tax, which was created to help pay for the Civil War. After gaining their independence from Britain, Americans were skeptical about giving the federal government absolute power to collect federal income taxes. As a result, early US tax laws dictated that direct taxes, like income taxes, had to be directly apportioned to a state's population. The nation went back and forth on its federal tax laws multiple times. For instance, in 1872, the income tax from the Civil War was repealed. But it was revived in 1894, and then repealed again in 1895. In 1913, Congress passed the 16th Amendment, giving Congress the power to levy income taxes on individuals and corporations without apportioning the burden among the states in line with population, once and for all.

Since 1913, Americans have paid income taxes at varying rates

In the 2020s, the top marginal tax rate has floated around 37%, relatively lower than previous eras. Some have called for boosting the rate significantly to tax the highest earners.

Read why some states are considering imposing a flat tax rate that isn't adjusted by income

Wisconsin was the first US state to impose a state income tax, close in time to when the federal income tax went into effect. Many states followed suit, but nine states to this day still don't levy wage-related taxes.

The IRS—a division of the US Treasury Department that enforces the Internal Revenue Code, collects taxes, and enforces tax laws—has been a frequent victim of arson over the years.

What America's 1% pays in taxes, by state

In the US, the top 1% of earners contribute 45% of all personal income taxes collected nationwide. But not all states are created equal when it comes to income tax. Some states are more dependent on the 1% than others for tax revenue. SmartAsset recently examined IRS tax return data to determine exactly how much the top 1% of earners in each state paid in taxes. Find your state here.

Americans between the ages of 45 and 55 pay nearly 30% of all income taxes, paying an average tax rate of around 17%.

The 16th Amendment paved the way for capital gains taxes

Ratified in 1913, the 16th Amendment paved the way for a far-reaching federal income tax and supercharged the country’s coffers. Before then, the US depended on import tariffs and so-called consumption taxes to raise revenue.

Individual income taxes are the federal government's primary revenue source, see a tracker that breaks down where the rest of the budget comes from

The US government historically makes nearly half of its total revenue last year from individual income taxes. But the US makes also makes money from a variety of other sources, including Medicare taxes and corporate income taxes. However, the federal government has run a deficit since 2001—reaching a peak of $3.13T in 2020.

Before the 16th Amendment, US tax law required direct taxes to be directly apportioned to a state's population

Due to these requirements, the federal government could not impose many direct taxes. Direct taxes include property and income taxes, whereas indirect taxes include duties and excises.

Death taxes have helped fund wars since the 1860s

Death taxes date back to 700 BCE and were used in Ancient Rome and Ancient Egypt. In the US, they've been used to finance wars since the Civil War, and have been levied on both the estate and beneficiary. The estate tax created during WWI to help finance war efforts is still in effect today.

See a timeline of the IRS's history, including the introduction of standard deductions and the digitization of the filing process

The Commissioner of Internal Revenue was created in 1862 to take over federal tax collection after the President enacted a temporary income tax. That agency eventually became today's Internal Revenue Service.

Tariffs once fueled the US economy, historically serving as a primary source of revenue and a means to protect domestic industries.

Capital gains taxes were first levied in the US in 1913

However, up until 1921, they were treated the same as ordinary income. Ever since then, rates have swung up and down.

How the federal income tax affected Prohibition

In the early 1900s, 30% to 40% of government tax revenue came from liquor, wine, and beer, a reliance that made Prohibition seem like a fiscal impossibility. But the passage of the federal income tax in 1913 changed the calculus, which helped allow the government to ban alcohol production and sales.

The most taxed states in America

Some states in the US have higher taxes than others. Hawaii, for instance, has the highest total tax burden in the country at 13.9%, whereas Alaska has the lowest overall tax burden at 4.9%. New York has the highest individual income tax burden; and eight states have no individual income tax. See a map of the most-taxed US states here.

80% of Americans are bothered that some wealthy people don't pay their fair share of taxes

That's according to data from Pew Research Center. While most people are primarily taxed on their wages, many people in America's 1% derive much of their income from investments instead, which are often taxed at preferential capital gains rates. This structure was shaped by a series of legislative cuts that began in earnest with the 1978 Revenue Act and the 1981 Economic Recovery Tax Act.

See how income taxes in the US compare to those of other countries.

The highest inflation ever recorded in US history was estimated at 30% in 1778, just after the Revolutionary War.

Charting where federal revenue comes from

About 50 percent of federal revenue comes from individual income taxes, 7 percent from corporate income taxes, and another 36 percent from payroll taxes that fund social insurance programs. See breakdown in charts here.

Understanding the low corporate tax rate in the US

Corporate taxes, which make up roughly a third of the federal government's revenue, have been calculated using a flat 21% rate since the Tax Cuts & Jobs Act of 2017. The current rate is considered low both by historic standards (it averaged over 50% in the 1950s and 1960s) and compared to other countries.

Opponents of the federal estate tax began using the term 'death tax' in the 1940s to sway public opinion.

Historically, only about 1% to 2% of Americans had to pay the federal estate tax

Recent IRS data shows that between 2011-16, that number dropped even lower: The federal estate tax only impacts about 0.2% of Americans. Death taxes typically only impact the rich, and the federal estate tax is no exception.

How World War II affects your wallet today

The world's deadliest conflict also impacted social programs extensively, including ways that still affect your money today. World War II is responsible for the practice of employers withholding tax payments and sponsoring health insurance, as well as the norm of providing school lunches for the nation's schoolchildren. Watch this brief video to learn more.

Revenue from tariffs goes to the US Treasury's general fund.

Watch this video to learn how US tax brackets actually work.

The federal government's decision to pay off the states' Revolutionary War debts required a new tax, which sparked an armed rebellion. 

Why the rich don't pay taxes like you do

The system behind the US income tax isn't as straightforward as it looks. You earn money. Taxes get taken out. Case closed … right? Not exactly. In this episode of "1440 Explores," we break down how the US tax system actually works, from confusing deductions and misunderstood tax brackets to why the wealthiest Americans often end up paying a very different tax than everyone else.

It cost the IRS $0.36 to collect $100 in 2024

It costs the IRS a significant amount of money to do part of its job—collecting money. For instance, the Internal Revenue Service spent $16.1B to collect $4.7T in taxes in 2023.

The .1% of Americans once controlled 7% of all US wealth. Today, they control closer to 18%.

The IRS already has much of the data it asks Americans to report when filing their taxes

Americans spend more than 7.9 billion hours per year doing their taxes: It's notoriously time-consuming, requiring forms, deductions, and often third-party help. But here's the twist: The IRS already has much of the data it asks you to report. Americans still have to do the work themselves partly due to big tax prep companies that lobby to keep the status quo.

Tax policy can have a direct impact on the national debt, with past presidents' changes to tax codes inflating the deficit.

Americans spend an average of $200 on tax preparation services like TurboTax and H&R Block

In 2025, about half of Americans were able to file taxes directly with the IRS for free. It was the second year of the agency's new program, which cuts out intermediaries. Though tax preparation has been free for many Americans, critics say tax companies upsell customers.

Learn how the US tax code works and why it's important

First published in 1926, the US Code is the official codification of federal statutes in the US. Title 26 of the US Code, for instance, lists all of the federal tax laws of the United States. A new edition is published every six years.

Hawaii and New York have the highest tax burdens out of all US states, both exceeding 12% of income

The term "tax burden" in this case refers to property, income, sales, and excise taxes as a share of total personal income. Alaska and New Hampshire have the lowest total tax burdens in the US, both falling below 6%.

The US has carried debt since 1791

After the Revolutionary War, the US owed $75M to nations like France. Debt builds when spending exceeds revenue, funding programs, wars, and economic recovery efforts. Most debt is domestic, like Social Security bonds, with foreign nations also holding a share.

See what it was like to live in the United States during World War II

In America, life was transformed by total war: sixteen million service members left civilian life, while massive industrial production demanded labor. Women, minorities, and teens filled factories, fueling boomtown growth and breaking social barriers. Simultaneously, rationing, recycling drives, Victory Gardens, ration stamps, blackout drills, and war bond campaigns permeated daily routines.

States with the highest (and lowest) tax rates

WalletHub researchers evaluated not just income taxes but real estate, sales, and other levies in order to rank every state by its total effective local and state tax rate (not including federal). Alaska scored the lowest total tax rate and Illinois...

Map of each state's largest tax revenue source

While America’s federal government primarily raises revenue through personal and corporate income taxes, it's a different story for each of the 50 states. This map shows how every state raises tax revenue for government activities. New York and California, for instance, raise most of that money through personal income taxes, whereas Texas and Florida have sales tax as their largest sources of tax revenue. Click here to see the map.

How much did WWII cost?

Though it lasted fewer than four years, World War II was the most expensive war in United States history, according to this infographic. Read through it to see how much WWII cost and learn about the consequences of financing such an expensive conflict.

About one dollar in every six that are owed to the federal government aren't paid each year

That adds up to close to $1T in what's known as the "tax gap." Read a breakdown on the main drivers of tax evasion (distinct from legal tax avoidance) in the US.

The Smoot-Hawley Tariff Act—which was passed during the Great Depression with the goal of reviving domestic industry—is among the most famous pieces of economic legislation in US history.

See how the federal estate tax has changed in the 21st century

In 2001, the government passed an act to completely repeal the tax. It was overturned in 2010. In 2017, the government increased the exemption threshold so fewer people would have to pay into the tax. In 2025, the exemption threshold was permanently set to $15M.

In addition to collecting taxes, issuing tax refunds, and performing audits, the IRS is tasked with enforcing the laws listed in the Internal Revenue Code

The Internal Revenue Code is also known as Title 26 of the US Code. It was enacted in 1925 and outlines income, estate, sales, payroll, and excise tax laws.

Most Americans take the standard tax deduction

A tax deductible is an expense that a taxpayer or business can subtract from adjusted gross income, reducing their taxable income and therefore reducing the amount of taxes owed. Governments often use tax deductibles as a way to reward people who do things that are considered beneficial to society, like charitable donations.

Warren Buffett paid a lower effective tax rate than his secretary

While wages and salaries are taxed progressively at rates up to 37%, long-term investments are taxed at lower rates: 0%, 15%, or 20%. For wealthy individuals like Buffett, whose income mainly comes from investments, this means paying a lower effective tax rate than someone earning a salary.

The US federal government employs roughly 3 million people

Tracking began in 1939, when the federal workforce consisted of about 1 million people. The total peaked in 1990 at 3.4 million, and hit a recent low in 2014 at 2.7 million.

US immigrants pay billions of dollars in taxes each year

While immigrants who are authorized workers pay taxes just like anyone else, even unauthorized workers file tax returns. These unauthorized workers use individual taxpayer identification numbers.

After emancipation, many slaves went from working for free to working for tips.

Use this calculator to find out the programs and services your federal income taxes fund.

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