The Sixteenth Amendment to the U.S. Constitution gives Congress the power to tax income directly, at the same rates in every state, without dividing the tax bill among the states by population. Ratified on February 3, 1913, its 30 words are the legal foundation for every dollar the IRS collects from your paycheck, your investments, and your business.1National Archives. 16th Amendment to the U.S. Constitution: Federal Income Tax (1913) The full text reads: “The Congress shall have power to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several States, and without regard to any census or enumeration.”
Why the Amendment Was Necessary
Before 1913, Article I, Section 9 of the Constitution required any “direct tax” to be divided among the states in proportion to their populations. If a state held five percent of the nation’s population, it could only be asked to contribute five percent of the total tax.2Constitution Annotated. Overview of Direct Taxes That made a broad income tax practically unworkable, because Congress would have had to set different rates in different states to hit each state’s population-based share.
When Congress passed an income tax in 1894, the Supreme Court struck it down. In Pollock v. Farmers’ Loan & Trust Co. (1895), the Court ruled that a tax on income from property was a direct tax and therefore had to be apportioned by population.3Justia. Pollock v. Farmers’ Loan and Trust Co. The 16th Amendment removed that obstacle. It didn’t invent a new taxing power; it eliminated the apportionment rule for income taxes so they could apply the same way to everyone, no matter where they live.4Legal Information Institute. Brushaber v. Union Pacific Railroad Someone earning $80,000 in Montana now owes the same federal income tax as someone earning $80,000 in New Jersey.
What Counts as Income
The phrase “from whatever source derived” is doing a lot of work. Congress translated it into statute through 26 U.S.C. §61, which defines gross income as all income from whatever source and then lists 14 categories to reinforce the point: compensation for services, business income, gains from property, interest, rents, royalties, dividends, annuities, and even income from the cancellation of a debt, among others.5Office of the Law Revision Counsel. 26 USC 61 – Gross Income Defined The list opens with “including (but not limited to),” so it is not exhaustive.
The Supreme Court pushed the definition further in Commissioner v. Glenshaw Glass Co. (1955), holding that gross income covers all gains that clearly increase a taxpayer’s wealth, regardless of the source. The case involved punitive damages from a lawsuit, which the taxpayer argued shouldn’t count as income. The Court disagreed, reasoning that Congress intended to reach every form of economic gain not specifically exempted.6Justia. Commissioner v. Glenshaw Glass Co., 348 U.S. 426 (1955) Under that standard, gambling winnings, prizes, found property, bartering income, and cryptocurrency profits all qualify. If you ended up wealthier than you started and the gain isn’t specifically excluded by statute, you owe tax on it.
What About Gains You Haven’t Cashed In?
A separate question is whether “income” requires you to actually receive a gain before it becomes taxable. The Supreme Court addressed this in Eisner v. Macomber (1920), defining income as “the gain derived from capital, from labor, or from both combined” and holding that a stock dividend didn’t count because nothing was severed from the investment and received by the shareholder.7Justia. Eisner v. Macomber, 252 U.S. 189 (1920) That case established a “realization” requirement.
Whether realization is a firm constitutional limit is still an open question. In Moore v. United States (2024), the Court upheld a one-time tax on the undistributed earnings of certain foreign corporations, rejecting a couple’s argument that they couldn’t be taxed on profits their overseas company had never paid out to them. The majority deliberately declined to rule on whether Congress could tax truly unrealized gains, like appreciation on stocks you haven’t sold.8Justia. Moore v. United States, 602 U.S. ___ (2024) For now, that question remains unresolved.
Why Rates Can Be Progressive
The 16th Amendment killed the apportionment rule, but Article I, Section 8 still requires that federal excises, duties, and imposts be “uniform throughout the United States.”9Constitution Annotated. Uniformity Clause and Indirect Taxes Uniformity means geographic uniformity, not mathematical equality. The Supreme Court settled this in Knowlton v. Moore (1900), ruling that graduated rates satisfy the uniformity requirement as long as the same rates apply in every state.10Justia. Knowlton v. Moore, 178 U.S. 41 (1900) That holding is why the federal income tax can charge higher rates on higher income.
2026 Federal Tax Brackets
The current system uses seven brackets. For 2026, the rates and income thresholds for single filers are:11Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
- 10% on income up to $12,400
- 12% on $12,401 to $50,400
- 22% on $50,401 to $105,700
- 24% on $105,701 to $201,775
- 32% on $201,776 to $256,225
- 35% on $256,226 to $640,600
- 37% on income over $640,600
These brackets are marginal, meaning only the income within each range is taxed at that rate. Someone earning $60,000 doesn’t pay 22 percent on the whole amount. They pay 10 percent on the first $12,400, 12 percent on the next chunk, and 22 percent only on the portion above $50,400. The 2026 standard deduction is $16,100 for single filers and $32,200 for married couples filing jointly, and it reduces your taxable income before the brackets apply.11Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
Filing Is Mandatory, Not Optional
The U.S. income tax system operates on self-assessment: you calculate your own tax liability and file your own return, rather than waiting for the government to send a bill. The IRS has sometimes described this arrangement as “voluntary,” and some people have seized on that word to argue they can opt out. Courts have flatly rejected that reading. “Voluntary” refers to who does the math, not whether the math is optional.12Internal Revenue Service. The Truth About Frivolous Tax Arguments – Section I (A to C)
The statutory filing requirement comes from 26 U.S.C. §6012, which sets income thresholds that trigger the obligation. For most people, the threshold roughly tracks the standard deduction. If your gross income is below that level you generally don’t have to file, though you may still want to if you’re owed a refund.
Penalties for Not Filing or Paying
Penalties escalate sharply depending on whether the IRS views your behavior as negligent, willful, or fraudulent.
On the civil side, failing to file on time triggers a penalty of 5 percent of the unpaid tax for each month the return is late, capped at 25 percent. Failing to pay on time adds a separate penalty of 0.5 percent per month, also capped at 25 percent. These stack, so someone who neither files nor pays owes both.13Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax
Criminal penalties are reserved for willful violations. Willfully failing to file a return or pay tax is a misdemeanor carrying a fine of up to $25,000 and up to one year in prison for each violation.14Office of the Law Revision Counsel. 26 U.S. Code 7203 – Willful Failure to File Return, Supply Information, or Pay Tax Willfully attempting to evade taxes is a felony punishable by up to $100,000 in fines and five years in prison.15Office of the Law Revision Counsel. 26 USC 7201 – Attempt to Evade or Defeat Tax Filing a fraudulent return or making false statements is a separate felony with fines up to $100,000 and up to three years in prison.16Office of the Law Revision Counsel. 26 USC 7206 – Fraud and False Statements
The distinction between “willfully failing to file” and “attempting to evade” is more than academic. A person who ignores their filing obligation year after year faces the misdemeanor charge. A person who hides income, invents deductions, or uses offshore accounts to conceal assets faces the felony evasion charge.
Arguments That Will Cost You Money
A cottage industry of “tax protest” theories has developed around the 16th Amendment, and none of them hold up in court. The IRS maintains a published list of arguments it considers legally frivolous.17Internal Revenue Service. The Truth About Frivolous Tax Arguments – Section I (D to E) Common ones include claims that the amendment was never properly ratified, that it doesn’t authorize a direct non-apportioned tax (it explicitly says “without apportionment”), that filing is voluntary, and that various “untaxing” kits or trusts let you withdraw from the system permanently.
Filing a return based on a position the IRS has identified as frivolous triggers a $5,000 penalty under 26 U.S.C. §6702, assessed automatically without any requirement that the IRS prove willfulness.18Office of the Law Revision Counsel. 26 USC 6702 – Frivolous Tax Submissions People who follow these theories often end up owing far more in penalties than they would have owed in taxes.