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 For instance, in 1872, the income tax from the Civil War was repealed. But it was revived in 1894, and then repealed again in 1895.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.

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

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.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

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.

Tariffs once fueled the US economy

US tariffs peaked in 1930 with the Smoot-Hawley Tariff Act, which slashed global trade by 65%. Once a key revenue source, tariffs gave way to income taxes in 1913, leading to decades of lower trade barriers. Today, US tariffs remain among the lowest worldwide.

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.

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.

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.

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

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.

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.

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

The .1% of Americans used to control 7% of all US wealth, but today, they control closer to 18%

Tax policy changes have likely contributed to the recent rise in the number of US billionaires. The average tax rate for the top 400 or so richest Americans is now about half of what it was 50 years ago in the 1970s, while the tax rates for the bottom 90% of Americans have not budged much at all.

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 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.

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.

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.

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

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.

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.

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.

Hollywood helped fund American military activity by boosting bond sales

To help fund its WWI military activity, the US introduced Liberty Bonds—government-issued debt marketed directly to the public. Starting at $50, the campaign targeted working Americans and offered Thrift Stamps to make bond-buying more accessible. Hollywood led the charge, with stars like Charlie Chaplin and Mary Pickford boosting bond sales.

Use this calculator to find out what your federal income taxes pay for

In the fiscal year 2024, the US federal government's biggest spending priorities included $1.5T on Social Security, $877B on national defense, and $874B on Medicare. This calculator from the Microsoft AI for Good Lab can help you estimate how your tax dollars are allocated across $6.8T in federal spending.