The 16th Amendment, explained in one line, is the constitutional provision that lets Congress tax your income directly, without dividing that tax among the states based on population. Ratified on February 3, 1913, it is the source of authority for every dollar of federal income tax collected today.1National Archives. 16th Amendment to the U.S. Constitution: Federal Income Tax (1913) Everything else in federal tax law, from the brackets on your paycheck to the penalties for filing late, sits on top of a single sentence added to the Constitution more than a century ago.
What the Amendment Says
The full text runs one sentence: “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.”2Constitution Annotated. Sixteenth Amendment
Three phrases carry the weight. “From whatever source derived” means Congress does not have to categorize or limit the types of income it reaches. “Without apportionment” removes the population-based formula that had blocked earlier income taxes. “Without regard to any census or enumeration” reinforces that no head count is needed before the tax can apply.
This language is the constitutional foundation for the Internal Revenue Code, which is Title 26 of the United States Code. The statutory definition of gross income mirrors the amendment’s breadth: it includes “all income from whatever source derived,” followed by a non-exhaustive list covering wages, business profits, rents, royalties, dividends, and more.3Office of the Law Revision Counsel. 26 USC 61 – Gross Income Defined Because the list is explicitly not limited to those categories, Congress can tax new forms of compensation, such as stock options, cryptocurrency, or gig-economy payments, as they emerge.
The Problem It Solved
Before 1913, the Constitution required that any “direct tax” be apportioned among the states by population. If the federal government wanted to raise $100 million through a direct tax, each state would owe a share based on its number of residents, regardless of how much wealth or income existed there.4Congress.gov. ArtI.S9.C4.1 Overview of Direct Taxes A state with one-twentieth of the nation’s population would owe one-twentieth of the tax, even if its residents earned far less than those in other states.
Congress tried an income tax anyway. The Income Tax Act of 1894 imposed a flat tax on incomes above $4,000, but the Supreme Court struck it down the following year in Pollock v. Farmers’ Loan & Trust Co. The Court held that a tax on income from property (rents, dividends, interest) was itself a direct tax that had to be apportioned.5Justia. Pollock v Farmers Loan and Trust Co, 157 US 429 (1895) Since the 1894 act made no attempt at apportionment, it was unconstitutional. Collecting income tax through apportionment was logistically absurd, and collecting it without apportionment was now illegal. The only fix was to amend the Constitution. Congress proposed the amendment in 1909, and ratification took nearly four years.
How Courts Define Income
The most important judicial definition came in Commissioner v. Glenshaw Glass Co. in 1955. The question was whether punitive damages counted as taxable income. The Supreme Court said yes, and announced a standard that has controlled tax law since: income includes all “undeniable accessions to wealth, clearly realized, and over which the taxpayers have complete dominion.”6Justia. Commissioner v Glenshaw Glass Co, 348 US 426 (1955)
Under that test, if something makes you wealthier and you can actually use or control it, you owe tax on it. Gambling winnings qualify. Prizes qualify. Win a car worth $40,000 on a game show, and the IRS treats that as $40,000 of income at fair market value.7Office of the Law Revision Counsel. 26 USC 74 – Prizes and Awards Bartered services count too. If a plumber fixes an electrician’s pipes in exchange for wiring work, both have received taxable income equal to the fair market value of what they got. Courts look at the economic reality of a transaction, not what the parties call it.
Realization: The One Big Limit
A significant boundary comes from Eisner v. Macomber in 1920. The Supreme Court held that “mere growth or increment of value in a capital investment is not income.”8Justia. Eisner v Macomber, 252 US 189 (1920) A rising stock price or appreciating home value is not taxable until you sell or exchange the asset. If you bought stock for $10,000 and it is now worth $15,000, you owe nothing on that $5,000 paper gain. Tax hits only when you sell.
Once you do sell an asset held longer than one year, the profit is taxed at long-term capital gains rates of 0%, 15%, or 20%, depending on your total taxable income. High earners may also face an additional 3.8% net investment income tax. Assets held one year or less are taxed at ordinary income rates.
Whether the Constitution actually requires realization before Congress can tax a gain is still an open question. The Supreme Court had a chance to settle it in Moore v. United States in 2024 and deliberately did not. The Moores challenged a one-time tax that attributed a foreign corporation’s undistributed profits to its American shareholders. The Court upheld the tax on narrow grounds: the corporation had realized the income, even if the shareholders had not personally received it.9Supreme Court of the United States. Moore v United States (2024) The Court declined to say whether a gain must be realized to qualify as “income” under the 16th Amendment, leaving proposals to tax billionaires on unrealized gains constitutionally untested.
What Actually Counts as Income
Federal law starts from the assumption that essentially everything is taxable. Gross income covers compensation, business profits, property gains, interest, rents, royalties, dividends, annuities, pension distributions, and income from canceled debts, among other categories.3Office of the Law Revision Counsel. 26 USC 61 – Gross Income Defined Income does not need to arrive as cash. Property, goods, and services all count.
The exceptions are specific statutory carve-outs. The common ones:
- Gifts and inheritances are not included in your gross income. Any income the gifted property later generates (rent, dividends, interest) is fully taxable to you.10Office of the Law Revision Counsel. 26 USC 102 – Gifts and Inheritances
- Life insurance death benefits paid to a beneficiary because of the insured’s death are generally excluded.11Office of the Law Revision Counsel. 26 USC 101 – Certain Death Benefits
- Compensatory damages for physical injuries are excluded. Punitive damages remain taxable under Glenshaw Glass.
- Interest on state and local government bonds is typically exempt from federal income tax.
These exclusions exist because Congress chose to grant them, not because the 16th Amendment lacks the power to reach them. Congress could repeal any of them.
How the Tax Gets Calculated in 2026
Gross income is not the number you pay tax on. Two rounds of subtractions come first. You reduce gross income by “above-the-line” adjustments, such as traditional IRA contributions, student loan interest, or HSA deposits, to arrive at your adjusted gross income (AGI). Then you subtract either the standard deduction or your itemized deductions, whichever is larger, to reach taxable income. That final number is what the brackets apply to.
For tax year 2026, the standard deduction is $16,100 for single filers, $32,200 for married couples filing jointly, and $24,150 for heads of household.12Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Most taxpayers take the standard deduction because it exceeds their itemizable expenses.
The federal income tax uses seven progressive brackets. Only the income within each bracket is taxed at that bracket’s rate. The 2026 rates are 10%, 12%, 22%, 24%, 32%, 35%, and 37%.13Internal Revenue Service. Federal Income Tax Rates and Brackets A single filer with $60,000 in taxable income does not pay 22% on the entire amount. The first portion is taxed at 10%, the next at 12%, and only the portion above the 22% threshold is taxed at 22%. Your effective rate ends up well below the marginal rate on your last dollar earned.
Penalties for Not Paying
Criminal prosecution is rare, but the tools exist. Tax evasion, meaning a willful attempt to avoid paying taxes you owe, is a federal felony. The tax code sets the fine at up to $100,000 for individuals, though a separate federal sentencing statute raises the ceiling to $250,000 for any felony conviction.14Office of the Law Revision Counsel. 26 US Code 7201 – Attempt to Evade or Defeat Tax15Office of the Law Revision Counsel. 18 USC 3571 – Sentence of Fine Imprisonment can reach five years, and courts can impose fine and prison time together. Willfully failing to file a return is a separate misdemeanor carrying up to one year in prison and up to $25,000 in fines.16Office of the Law Revision Counsel. 26 USC 7203 – Willful Failure to File Return, Supply Information, or Pay Tax
The penalties most people encounter are civil. Filing a return late triggers a penalty of 5% of the unpaid tax for each month the return is overdue, capping at 25%.17Internal Revenue Service. Failure to File Penalty If a return is more than 60 days late, the minimum penalty for returns due in 2026 is $525 or 100% of the unpaid tax, whichever is less.18Internal Revenue Service. Topic No 653 – IRS Notices and Bills, Penalties and Interest Charges
Paying late is penalized separately at 0.5% of the unpaid balance per month, also capping at 25%. When both penalties run at once, the late-filing penalty drops by 0.5% so the combined monthly hit stays at 5%. Interest compounds on top of everything. For the first quarter of 2026, the IRS charges 7% annual interest on underpayments, dropping to 6% in the second quarter.19Internal Revenue Service. Quarterly Interest Rates Interest never caps. It runs until the balance is paid.
Arguments That the Amendment Is Invalid
A persistent fringe movement claims the 16th Amendment was never properly ratified, that it doesn’t authorize taxing wages, or that filing a return is voluntary. Courts have rejected every version of these arguments for decades, and the IRS keeps an official list of positions it treats as legally frivolous.20Internal Revenue Service. The Truth About Frivolous Tax Arguments – Section I (D to E) The ratification challenge, often built around alleged punctuation errors or procedural defects in state votes, is on that list by name.
Filing a return based on one of these arguments carries a $5,000 penalty per frivolous submission, and the IRS does not need to take you to court to impose it.21Office of the Law Revision Counsel. 26 USC 6702 – Frivolous Tax Submissions Every federal circuit court has upheld the amendment’s validity and the income tax it authorizes.