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

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.

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 For instance, in 1872, the income tax from the Civil War was repealed. But it was revived in 1894, and then repealed again in 1895.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

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.

Read why the information Americans have about our tax system might be misleading

For many, filing taxes can be complicated and overwhelming. Some argue that the tax system obscures certain aspects of the US tax code, making it difficult for taxpayers to accurately assess potential reforms.

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.

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

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.

Learn about loopholes in the American tax code, which involve everything from cat food to death to heavy machinery.

401(k) is a section of the US tax code

How did 401(k) plans get their name? Check out the 401(k) section (and subsection) of the US tax code made famous by benefits consultant Ted Benna. Tap into your inner accountant and check out the now-famous portion of the dense, 10,000-section tome that is the Internal Revenue Code.

Read through the actual text of the US Constitution

This helpful guide from the US Congress includes annotations that provide valuable insights into the background, crafting, and legacy of each article in the document. Additionally, the resource offers accessible legal analysis and interpretations.

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.

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.

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.

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.

The history of bankruptcy in the US dates back to the signing of the Constitution

In 1787, this founding document gave Congress the right to establish nationwide bankruptcy laws. Legislators took advantage of that power in 1800 when they passed the Bankruptcy Act of 1800, the first comprehensive bankruptcy law at the federal level.

Congress has the power to enact laws related to bankruptcy, thanks to the US Constitution

It has done just that since 1800. This legislation, which outlines the various types of bankruptcy filings, has evolved over time. The most recent iteration is the Bankruptcy Reform Act of 1978, which introduced Chapter 11 filings in an effort to make the process easier for businesses and individuals.

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.

The United States is the world's oldest continuously operating federal system under a written constitution

The US pioneered federalism in the late 18th century, and many countries later adopted federal systems to manage conflict and share power. This resource features interactive maps that trace the spread of federal systems worldwide from 1900 to the present.

Read an overview of US tariff policy before the second Trump Administration

This comprehensive report from the Congressional Research Service explores the evolving role of tariffs—from a major source of government revenue to a tool for trade and foreign policy—providing insights into current practices, legal foundations, and global trade dynamics.

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

Visualizing US state taxes in seven charts

Ever wondered how your state’s tax system compares to others? Here’s an overview of the US state tax system based on seven visualizations.

The US dollar is the official currency of the United States and is the most circulated currency around the world

The US dollar was established in 1792 and comes in the form of coins or paper money. It's considered one of (if not the most) stable currencies in the world due to America’s strong and robust economy, as well as its relatively stable government.

Read more about how the IRS is organized

The Internal Revenue Service is led by a commissioner, who leads the IRS for a five-year term after being selected by the president of the United States. Under the commissioner, the IRS has multiple subdivisions that work on different tax groups, such as the Wage and Investment Division to handle individual wage earners.

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

In 2019, Congress passed the Secure Act to reform key aspects of the US tax code

Key Secure Act provisions included raising the age at which mandatory distributions take effect (to increase saving), allowing larger catch-up contributions for older individuals, and allowing employers to directly match contributions in a Roth 401(k).

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.

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

The US Constitution has been amended 27 different times since its ratification

Dive deeper into each amendment to the Constitution with resources provided by the National Constitution Center. This website features podcasts, videos, and other web resources for each of the amendments, examining their creation and their impact on today’s political and social landscape.

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.

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.

Congress meets and legislates in the US Capitol building

The United States Capitol reflects neoclassical ideals drawn from ancient Greece and Rome. First opened to Congress in 1800 and repeatedly expanded over time, it remains the symbolic and functional home of both The House and The Senate.

The US framework of government has influenced the constitutions of many other countries

In 1787, the US Constitution introduced a system built on the separation of powers and individual liberties, including freedom of speech and religion. Though widely influential, its rigidity has made it less of a modern model as countries adopt more adaptable constitutional frameworks.

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.

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.

How US currency is issued

Cash in the US is the result of a collaborative process between the Federal Reserve, the Treasury Department, regional banks, and a little-known agency called the Bureau of Engraving and Printing. From design to issuance, learn the steps in currency production in the US with this smart, aesthetic interactive.

Roughly 22% of US tax dollars go to Social Security

Social security is the US government’s largest expense. You can see other government expenses in a visual breakdown of what one US tax dollar actually pays for. Total spending amounts were converted to cents on the dollar and percentages.

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.

The Budget and Accounting Act of 1921 created the modern federal budget

Before 1921, federal funding was fragmented and ad hoc. This article traces how inefficiency and postwar pressures led Congress to pass the Budget and Accounting Act, creating a standardized, centralized federal budgeting process.

Created in 1862, the IRS has a scandalous history

From Al Capone's tax evasion to corruption and bribery within the IRS, the government agency has had its fair share of scandals. This article details many of them, outlining corruption that reveals this seemingly boring agency as anything but.

Read a breakdown of the different financial and banking regulatory bodies in the US, including the SEC.

What it's like to do your own taxes for the first time

Most Americans across the country have one thing in common: They hate doing their taxes. Many use an accountant or an online service like TurboTax to avoid doing taxes themselves. In this video, two journalists decide to do their taxes on their own for the first time.

What is a 401(k)?

Should you get a 401(k)? To make sense of this obscure piece of tax code, here’s a beginner’s guide to one of the more common forms of retirement savings in the US. Learn the history of the 401(k), how to sign up for one, the different types, and more in this well-organized and concise explainer from Investopedia.

The Constitution gives Congress sweeping control over the federal budget

Article I, Section 8's Spending Clause authorizes Congress to tax, pay debts, and promote the "common Defence and general Welfare," making it one of Congress's most powerful tools—and the constitutional foundation of federal budget control.

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.

Watch a breakdown of tax breaks most Americans don't know about

Programs like healthcare savings accounts or flexible spending accounts are tax-free accounts that are designed to help lower healthcare costs. However, many Americans don't use them and don't understand how they work.

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.

Half of the richest people in the US are finding ways around death taxes

One of the main purposes of the federal estate tax is to crack down on generational wealth, so wealth isn't concentrated among a select few. However, the ultra-rich have found ways around paying these taxes. This ProPublica article investigates the practices used by half of the 100 richest people in the US to avoid death taxes.