The law that requires you to pay federal income taxes is Section 1 of the Internal Revenue Code, which states that “there is hereby imposed on the taxable income of every” individual a tax at rates Congress sets. That statute takes its constitutional authority from the Sixteenth Amendment, ratified in 1913, which gave Congress the power to tax incomes without apportioning the tax among the states. Other sections of the same code define what income is, decide who has to file, and set the penalties for people who don’t.
The Constitutional Authority
Congress’s power to raise revenue is older than the income tax itself. Article I, Section 8 of the Constitution lets Congress “lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States.”1Cornell Law Institute. Article I of the U.S. Constitution The problem with an income tax under that original text was a requirement that certain taxes be split among the states by population, which made a uniform tax on individual incomes practically impossible.
The Sixteenth Amendment removed that obstacle. Ratified on February 3, 1913, it gives Congress the power “to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several States.”2National Archives. 16th Amendment to the U.S. Constitution: Federal Income Tax (1913) Every federal income tax law since then rests on that one sentence.
Section 1: The Statute That Imposes the Tax
The Sixteenth Amendment gave Congress permission. The law that actually taxes you is Section 1 of the Internal Revenue Code, which is Title 26 of the United States Code.3Office of the Law Revision Counsel. Browse the United States Code – Title 26 Internal Revenue Code The section opens with the words “there is hereby imposed on the taxable income of” and then sets out the rates for each filing status: married couples filing jointly, heads of households, single filers, and married individuals filing separately.4Office of the Law Revision Counsel. 26 USC 1 – Tax Imposed That is the direct answer to the question of what makes you pay: Section 1 imposes the tax, and the rest of Title 26 fills in who owes, how much, and when.
The Internal Revenue Service administers and enforces those rules under Section 7801 of the same code.5Internal Revenue Service. The Agency, Its Mission and Statutory Authority Congress writes the tax; the IRS collects it.
What the Law Treats as Income
Section 61 of the Internal Revenue Code defines gross income as “all income from whatever source derived,” unless another section of the code specifically excludes it.6Office of the Law Revision Counsel. 26 USC 61 – Gross Income Defined That wording is deliberately wide. The default is that anything of economic value coming into your hands is taxable, and you have to point to a specific statute to change that.
Section 61 lists 14 examples to illustrate: wages, business profits, gains from selling property, interest, rent, royalties, dividends, annuities, pensions, canceled debt, and others.6Office of the Law Revision Counsel. 26 USC 61 – Gross Income Defined The list is not exhaustive. Gambling winnings, barter income, cryptocurrency gains, and prize money all count even though the statute doesn’t name them. Section 102 carves out some familiar exceptions, most notably gifts and inheritances, though the exclusion covers the property received, not the income it later produces.7Office of the Law Revision Counsel. 26 USC 102 – Gifts and Inheritances
Who Has to File, and Why “Voluntary” Doesn’t Mean Optional
Section 6012 of the Internal Revenue Code identifies who has to file a return. The general rule is that if your gross income for the year reaches the standard deduction for your filing status, you file.8Office of the Law Revision Counsel. 26 USC 6012 – Persons Required to Make Returns of Income Self-employed people have a lower trigger: net self-employment income of $400 or more requires a return regardless of the broader threshold.9Internal Revenue Service. Check If You Need to File a Tax Return
You’ll sometimes hear the U.S. income tax called a system of “voluntary compliance,” and the phrase confuses people. It doesn’t mean paying is optional. It means the law puts the arithmetic on you: you calculate what you owe, prepare the return, and send the payment without waiting for a bill. Section 6151 makes this explicit, requiring anyone who has to file a return to “without assessment or notice and demand from the Secretary, pay such tax” when the return is due.10Office of the Law Revision Counsel. 26 USC 6151 – Time and Place for Paying Tax Shown on Returns The self-reporting is voluntary. The obligation behind it is not.
What Happens if You Don’t Pay
The consequences split into two tracks: civil penalties that pile onto your tax bill, and criminal charges for willful violations.
Civil Penalties
Filing late without a valid extension costs 5% of the unpaid tax for each month or partial month the return is overdue, up to 25%. If the return is more than 60 days late, the minimum penalty is the lesser of $435 or the full tax owed. Filing on time but paying late is cheaper: 0.5% per month on the unpaid balance, also capping at 25%.11Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax Interest runs on top of both, set quarterly and compounded daily.12Internal Revenue Service. Quarterly Interest Rates The practical lesson: file even if you can’t pay, then work out the balance.
Fraud is treated separately. If any part of an underpayment is due to fraud, the penalty is 75% of the fraudulent portion.13Office of the Law Revision Counsel. 26 USC 6663 – Imposition of Fraud Penalty
Criminal Penalties
Willfully failing to file a return, keep required records, or pay the tax is a misdemeanor under Section 7203, with fines up to $25,000 and up to one year in prison.14Office of the Law Revision Counsel. 26 USC 7203 – Willful Failure to File Return, Supply Information, or Pay Tax Tax evasion under Section 7201 is a felony, with fines up to $100,000 for individuals ($500,000 for corporations) and up to five years in prison.15Office of the Law Revision Counsel. 26 USC 7201 – Attempt to Evade or Defeat Tax
The line between civil and criminal is intent. Honest mistakes and careless errors generally stay in the civil column. Criminal prosecution is reserved for deliberate conduct: false Social Security numbers, two sets of books, fabricated deductions, hidden accounts. IRS auditors call these signs “badges of fraud.”
Arguments That the Law Doesn’t Apply
Because this question is one tax protesters frequently ask, the arguments circulating online deserve a direct answer. Two come up most often.
The first is that filing is “voluntary.” It isn’t, in the sense that word usually carries. Section 6151 requires payment without waiting for a bill, and Section 6012 requires the return. The self-reporting is what’s voluntary; the tax itself is mandatory.
The second is that wages aren’t income. Section 61 says gross income is “all income from whatever source derived,” and courts have consistently held that wages, salaries, and other compensation for personal services fall inside that definition.
Filing a return built on any of these theories carries its own $5,000 penalty for a frivolous submission, on top of the tax owed, interest, and any other penalty that applies.16Internal Revenue Service. The Truth About Frivolous Tax Arguments The people following that advice don’t end up tax-free. They end up owing more.