The Essential Guide to Understanding Taxes

Essential: In 2019, economists Emmanuel Saez and Gabriel Zucman of the University of California, Berkeley, published a book with a quietly devastating title: The Triumph of Injustice. Its central finding was not a projection or a model - it was a historical fact, derived from exhaustive reconstruction of US tax data going back to 1913.

For the first time in recorded American history, the 400 wealthiest Americans paid a lower effective tax rate than working-class families when all taxes - federal, state, local, and payroll - were counted together.

The Forbes 400 paid an effective total tax rate of approximately 23 percent.^[1] The bottom half of American earners, people making less than $50,000 a year, paid approximately 24 percent. The pattern held even accounting for the value of government transfers and services.

The progressive income tax that Americans argue about so intensely - with its top federal marginal rate of 37 percent, its rhetoric of asking the wealthy to pay their fair share - had been offset so thoroughly by other elements of the tax system that the system as a whole was functionally flat, or even regressive, at the very top.

The chart that accompanied this finding became one of the most discussed visualizations in political economy.

It showed a U-shaped curve: the bottom deciles of the income distribution paid moderate effective rates on their modest incomes, the middle and upper-middle class paid the highest effective rates, and then rates curved back down as income approached the very top.

It inverted the common assumption about what the American tax system does. The assumption was that high statutory top rates on ordinary income meant the wealthy paid proportionately more.

The reality was that wealthy individuals derive most of their income not as ordinary income but as capital gains and dividends taxed at preferential rates, shelter gains in unrealized appreciation that is never taxed, benefit from a payroll tax that caps out well below the income levels where wealth is concentrated, and pay far lower effective state and local tax rates because they spend a smaller share of their income on taxable consumption.

Saez and Zucman were not neutral observers - they were committed to progressive redistribution and their book proposed a wealth tax as a solution.

But the underlying data they assembled, using IRS records, Federal Reserve flow-of-funds accounts, and national income statistics, was reviewed and substantially accepted by economists across the political spectrum.

The finding about effective rates was largely acknowledged. The disagreement was about what to do, not about what was happening.

Understanding taxes requires understanding what this finding reveals: that the relationship between tax law as written and tax burden as experienced is mediated by a dense thicket of rates, bases, exemptions, credits, deductions, and cross-jurisdictional strategies that can make high statutory rates compatible with low effective burden.

"The tax system has become a tool for the wealthy to accumulate ever-greater fortunes while the rest of society foots the bill.^[11] This is not a natural consequence of markets - it is a policy choice." - Emmanuel Saez and Gabriel Zucman, The Triumph of Injustice (2019)

Key Definitions

Marginal tax rate - The rate applied to the last dollar of income within a tax bracket. This is the rate that applies to additional income earned, not to total income. Under a graduated schedule, all income below the bracket threshold continues to be taxed at lower rates.

Effective tax rate - Total taxes paid divided by total income. The average rate across all income, always lower than the top marginal rate under a progressive schedule. This is the figure that matters for comparing tax burdens across income levels.

Tax incidence - Who actually bears the economic burden of a tax, as distinct from who legally remits it. A tax on corporate profits is legally paid by corporations, but the economic burden falls on some combination of shareholders, workers, and consumers depending on market conditions and capital mobility.

Progressivity - A tax structure in which higher-income individuals pay a larger percentage of their income. The opposite, regressivity, describes a structure in which lower-income individuals pay a larger share.

Capital gain - The profit realized when an asset is sold for more than its purchase price. Long-term capital gains - on assets held for more than one year - are taxed at preferential rates substantially below ordinary income rates in the United States.

Stepped-up basis - A provision in US tax law allowing heirs to inherit assets at current market value, eliminating all capital gains tax liability on appreciation that accumulated during the decedent's lifetime.

Tax expenditure - A reduction in tax liability resulting from a deduction, exclusion, credit, exemption, or preferential rate. Economically equivalent to direct government spending but delivered through the tax code and receiving far less legislative scrutiny.

Deadweight loss - The efficiency cost of taxation - the value of economic transactions that would have occurred in the absence of a tax but do not occur because the tax makes them unprofitable.

Major Tax Types Compared

Why Governments Tax

Before examining how taxes work mechanically, it is worth asking why governments tax at all. Public economists identify four major rationales.

The first is revenue: governments provide public goods - national defense, courts, basic infrastructure, public health systems - that private markets will not produce adequately because they are non-excludable and non-rival.

Once a clean water system exists, it is difficult to exclude users and one person's consumption does not diminish another's.

These characteristics make private provision economically infeasible at efficient scale. Compulsory taxation funds collective provision. For more on the economics of public goods, see what are public goods.

The second is redistribution: market outcomes generate substantial inequality that societies may judge excessive on grounds of fairness, social cohesion, or aggregate welfare. Progressive taxes combined with targeted transfers can reduce this inequality.

The appropriate degree of redistribution involves both empirical questions (how much does inequality harm economic performance?) and normative ones (how much inequality is acceptable?).

The third is externality correction: markets produce too much of activities that impose costs on others - carbon emissions, tobacco, traffic congestion - and too little of activities that generate benefits for others - research, education, vaccination.

Taxes on the former and subsidies on the latter, implemented through tax credits, can align private incentives with social welfare.

The fourth is macroeconomic stabilization: in a Keynesian framework, automatic stabilizers in the tax code reduce effective tax burdens during recessions (increasing private purchasing power) and raise them during expansions, dampening the business cycle without requiring discretionary legislative action.

Income Taxes: The Progressive Rate Structure

The US federal income tax uses a graduated bracket structure with seven rates. For 2024, the rates are 10%, 12%, 22%, 24%, 32%, 35%, and 37%, applied to successively higher bands of taxable income. The crucial point is that the marginal rate applies only to income within a specific range, not to all income.

A single filer moving from $44,000 to $45,000 in taxable income does not pay 22% on $45,000 - they continue to pay 10% on the first $11,600, 12% on the next $35,550, and 22% only on the final dollar above $47,150.

This architecture is widely misunderstood. Polls consistently find that significant minorities of Americans believe that earning more money can result in lower after-tax income by pushing them into a higher bracket. This is mathematically impossible under a graduated rate structure.

The bracket rate applies only to income within that bracket, so each additional dollar earned always yields a positive after-tax amount.

The gap between marginal and effective rates is substantial. A single filer with $200,000 in taxable income faces a top marginal rate of 32% but an effective federal income tax rate of roughly 19%. A married filer with $600,000 in taxable income faces a top marginal rate of 37% but an effective rate of around 28%.

The effective rate always lies below the marginal rate because lower-bracket income continues to be taxed at its applicable lower rates.

The Earned Income Tax Credit: Negative Income Tax in Practice

The Earned Income Tax Credit is among the largest anti-poverty programs in the United States, providing refundable tax credits to working people with low to moderate incomes.

It functions as a de facto negative income tax: qualifying workers with children receive credits that can exceed their total income tax liability, resulting in a net transfer payment from the government. For 2024, the maximum EITC for a family with three or more children is approximately $7,830.

The EITC phases in with earnings - rewarding work - reaches a plateau, and then phases out as income rises toward middle-income levels. The phaseout creates effective marginal rates on affected workers that can exceed their statutory income tax bracket rate, a technical problem that tax economists have long debated.

The program has strong empirical evidence for effectiveness in reducing poverty and increasing labor force participation, particularly among single mothers.

Raj Chetty and colleagues, analyzing administrative tax data, found that the EITC had significant positive effects on intergenerational mobility for children in beneficiary households, suggesting that the anti-poverty effects extend across generations.^[9]

Capital Gains: The Preferential Rate and Its Consequences

The distinction between ordinary income and capital gains income is the single most important structural feature producing the disparate effective rates documented by Saez and Zucman. Workers who receive wages pay ordinary income tax at rates up to 37%.

Investors who receive long-term capital gains and qualified dividends pay 0%, 15%, or 20% - rates that cap far below the top rate on ordinary income.

The origins of this preference lie in two arguments. First, many capital gains represent inflation-adjusted returns rather than real gains - if an asset purchased for $100 in 1990 is sold for $200 today, some portion of that $100 gain reflects general price-level increases rather than real economic return.

Taxing the full nominal gain at ordinary income rates arguably overtaxes the real return. Second, capital formation is argued to be sensitive to tax rates: lower rates on capital gains are claimed to encourage investment and entrepreneurship by improving after-tax returns.

Both arguments have merit in principle; both are also substantially weaponized in political debate to justify rates far below what the economic logic would support.

The Carried Interest Loophole

One of the most contested features of the capital gains preference is carried interest: compensation paid to private equity and hedge fund managers as a share of investment profits rather than a fixed management fee.

Although carried interest is clearly compensation for services - the fund manager earns it through work managing others' capital - it is treated as capital gains under current US tax law rather than ordinary income.

Fund managers earning tens or hundreds of millions in annual compensation pay 20% on their primary income rather than the 37% rate that would apply to a highly paid surgeon or corporate attorney earning the same amount as a salary.

This disparity has been criticized across the ideological spectrum. Presidents of both parties have proposed eliminating it; Congress has repeatedly preserved it under lobbying pressure from the private equity industry.

The Joint Committee on Taxation estimated that taxing carried interest as ordinary income would raise approximately $180 billion over a decade.^[10]

Unrealized Gains and Stepped-Up Basis

An even larger structural advantage for the wealthy is the treatment of unrealized capital gains. US tax law taxes capital gains only when an asset is sold - a realization-based rather than accrual-based system.

This creates the "buy, borrow, die" strategy used by ultra-wealthy individuals to minimize lifetime tax liability: hold appreciated assets without triggering capital gains tax; borrow against them using the assets as collateral (loans are not income and not taxable); hold until death, at which point the stepped-up basis rule allows heirs to inherit assets at current market value, completely eliminating the capital gains accumulated over a lifetime.

The mechanism is legally straightforward and entirely legal. An individual who purchased Amazon shares in 1997 and held them to death in 2030 would owe zero capital gains tax on decades of appreciation. The heirs inherit at the 2030 value; if they sell immediately, they owe nothing.

In aggregate, the step-up in basis forgives an estimated $100 billion or more in capital gains taxes annually.

Payroll Taxes: The Hidden Regressive Element

The Federal Insurance Contributions Act (FICA) taxes fund Social Security and Medicare. For Social Security in 2024, the combined rate is 12.4% (6.2% each from employer and employee) applied to wages up to the taxable maximum of $168,600.

Above this cap, no additional Social Security tax is owed regardless of earnings. For Medicare, the 2.9% rate applies to all wages without a cap, with an additional 0.9% surtax on high earners.

This structure creates a steeply regressive pattern above the Social Security cap. A worker earning $80,000 pays the full 12.4% Social Security rate on all of their wages. A worker earning $1 million pays the same tax on only the first $168,600, meaning the Social Security component falls to roughly 2% of their total wages.

When combined with Medicare (which does apply to all wages), this payroll tax structure means that middle-income workers face combined payroll tax rates of roughly 15% - while high earners' effective payroll rate falls with rising income.

This is not incidental. It contributes substantially to the Saez and Zucman finding about the U-shaped total effective rate curve. When FICA taxes are included in calculations of total tax burden - as they should be, since they are a mandatory government levy - the progressive character of the federal income tax is substantially offset.

Corporate Taxes: Legal Liability Versus Economic Incidence

The corporate income tax illustrates the distinction between legal and economic incidence with particular clarity. A corporation can legally remit taxes to the government.

But corporations are owned and operated by people, and the economic burden of a corporate tax ultimately falls on some combination of shareholders, workers, and consumers.

Who bears the corporate tax depends critically on how mobile capital is across jurisdictions. In a closed economy where capital cannot move internationally, a corporate tax reduces returns on domestic investment and falls primarily on capital owners - shareholders.

In an open global economy where corporations can credibly shift investment to lower-tax locations, the burden analysis changes: if capital mobility is high, a corporate tax may be partially shifted onto workers through reduced investment and wages.

The empirical literature has produced a wide range of estimates. Studies by economists including Larry Katz and Alan Krueger suggest that workers bear 20% to 40% of corporate tax burden through lower wages in a mobile-capital world; other researchers place the worker share higher or lower depending on assumed capital mobility.

The Congressional Budget Office uses an assumption that capital owners bear about 75% of the burden and workers bear about 25%.^[4]

This debate has direct policy implications. If workers bear significant corporate tax burden, then the 2017 Tax Cuts and Jobs Act's reduction of the corporate rate from 35% to 21% - sold as a benefit to shareholders - may also have benefited workers through increased investment and wage growth.

Proponents made this argument at the time. The evidence on whether the TCJA produced the promised wage growth was mixed; the nonpartisan Congressional Budget Office found that the TCJA substantially increased the federal deficit rather than paying for itself through growth, adding an estimated $1.9 trillion to deficits over the decade following passage.^[5]

The Reasons Wealthy Americans Pay Lower Effective Rates

The Saez and Zucman finding - that effective tax rates become flat or regressive at the very top of the income distribution - is explained by several intersecting mechanisms.

First, the wealthy receive most of their income as capital gains and qualified dividends taxed at 20% rather than as wages taxed at up to 37%. As income rises above a certain threshold, the composition of income shifts from labor to capital.

Second, unrealized capital gains and stepped-up basis mean that substantial appreciation in wealth is never taxed at all. Forbes 400 members hold the majority of their wealth in appreciated equity; the annual increase in value of those holdings is not taxable income.

Third, the Social Security payroll tax cap at $168,600 means that earners above that threshold pay a progressively smaller share of total income in payroll taxes. For someone earning $10 million, the Social Security component represents less than 0.1% of income.

Fourth, sales taxes - imposed by states and localities - are regressive because lower-income households spend higher fractions of their income on consumption.^[7]

A family earning $40,000 may spend 90% on consumption and pay sales tax on most of it; a family earning $10 million saves and invests most of their income and faces sales tax on only a small fraction.

Fifth, the 2017 TCJA reduced the corporate tax rate from 35% to 21%, benefiting shareholders disproportionately. Combined with the lowering of the top pass-through business income rate through a 20% deduction, the TCJA disproportionately reduced taxes on income derived from capital ownership.

All of these mechanisms compound. Individually, each might be defended on some theoretical ground. Collectively, they produce a system in which the wealthiest Americans pay effective total tax rates comparable to or below middle-class workers.

The Laffer Curve: A Legitimate Insight, a Political Weapon

The Laffer curve describes the relationship between tax rates and tax revenue as a non-linear function. At a tax rate of 0%, revenue is zero. At a rate of 100%, revenue is also effectively zero - nobody works or invests if the government takes everything.

Between these extremes, there is some rate that maximizes revenue; above that rate, further rate increases reduce revenue by shrinking the taxable base.^[6]

Arthur Laffer famously sketched this concept on a napkin at a Washington restaurant in 1974, in a meeting with Dick Cheney and Donald Rumsfeld.

The insight itself is mathematically unassailable and has legitimate theoretical content: there is indeed a revenue-maximizing rate, and if current rates are above it, a rate cut could theoretically increase revenue.

The problem is empirical. The theoretical insight says nothing about where the revenue-maximizing rate actually is. If it is at 80%, then rates below 80% are on the "right side" of the curve, and rate increases raise revenue. If it is at 30%, then rates above 30% are on the "wrong side," and cuts raise revenue.

The academic literature, synthesized by economists including Peter Diamond and Emmanuel Saez, suggests that the revenue-maximizing top marginal rate on ordinary income is somewhere in the 70-80% range - well above current US top rates of 37%.^[3]

At current US rates, the empirical evidence consistently shows that rate cuts reduce revenue rather than increasing it, contrary to the supply-side argument.

The 1981 Reagan tax cuts, which reduced the top marginal rate from 70% to 28% over several years, were accompanied by large deficits, not the revenue surge that supply-side proponents predicted.

The 2017 TCJA, which cut the corporate rate from 35% to 21%, increased the federal deficit by approximately $1.9 trillion over its first decade according to CBO projections.

Neither episode demonstrates the self-financing revenue response that the supply-side application of the Laffer curve predicts.

International Tax Avoidance and the Global Minimum Tax

The globalization of corporate operations has created enormous opportunities for tax avoidance through profit shifting to low-tax jurisdictions. Transfer pricing - the prices charged for transactions between subsidiaries of the same multinational corporation - is the primary mechanism.

A pharmaceutical company that develops a drug in the United States can license the intellectual property to an Irish subsidiary at a low intercompany price, then allow the Irish entity to earn the royalties and profits taxed at Ireland's low corporate rate.

The drug's profits are effectively shifted from the high-tax jurisdiction where the research occurred to the low-tax jurisdiction where an IP holding company was established.

Gabriel Zucman's research, published in The Hidden Wealth of Nations (2015) and subsequent academic papers, estimated that approximately $7.6 trillion in household financial wealth was held offshore in tax havens, sheltered from taxation in home countries, and that roughly 40% of multinational corporate profits globally were booked in tax havens.^[2]

The revenue loss to high-tax countries is estimated in the hundreds of billions annually.

The OECD's Base Erosion and Profit Shifting (BEPS) project, launched in 2013, produced a series of reforms including strengthened transfer pricing rules, limits on interest deductibility to discourage debt-shifting strategies, and requirements for country-by-country reporting of profits and taxes paid.

The culminating achievement was the Pillar Two agreement - a global minimum corporate tax of 15% - reached in October 2021 by 137 countries representing more than 90% of global GDP.

Pillar Two requires that multinationals pay at least 15% on profits in every jurisdiction in which they operate, with home-country governments imposing top-up taxes where foreign jurisdictions tax at lower rates.^[8]

The practical implementation of Pillar Two has proven complex, and tax lawyers have identified multiple strategies for minimizing its impact through substance requirements, qualified refundable tax credits, and other mechanisms.

Whether it substantially reduces profit shifting in practice depends on enforcement rigor in signatory countries and on whether major holdout jurisdictions - including some US states and certain island tax havens - maintain carve-outs.

Tax Expenditures: The Hidden Welfare State

The US tax code contains hundreds of provisions reducing tax liability relative to a comprehensive income baseline - collectively called tax expenditures.

These include the mortgage interest deduction, the exclusion of employer-provided health insurance premiums from taxable income, the deduction for charitable contributions, preferential treatment of retirement account contributions, and many others.

The Office of Management and Budget estimates that major federal tax expenditures total more than $1.5 trillion per year - roughly comparable to the entire discretionary federal budget.

Tax expenditures are economically equivalent to direct government spending programs, but they receive far less political scrutiny.

Because they reduce taxes rather than increase expenditures, they are invisible to analyses focused on the "size of government." They also tend to be regressive in their incidence: deductions are worth more to taxpayers in higher brackets, and many tax expenditures target activities - homeownership, retirement savings, employer health insurance - that are more common and more generously utilized among higher-income households.

The mortgage interest deduction overwhelmingly benefits homeowners with large mortgages on expensive properties; renters receive nothing.

Stanley Surrey, the Treasury Department official who coined the term "tax expenditure" in the late 1960s, argued that if these provisions were explicit spending programs they would receive proper appropriations scrutiny rather than persisting indefinitely as invisible subsidies; that argument has not triumphed.

Related Articles

For the structural forces driving rising wealth concentration that tax policy shapes, see what is inequality. For the public goods and services that taxation finances, see what are public goods.

Sources & Further Reading

1. Saez, E., & Zucman, G. (2019). The Triumph of Injustice: How the Rich Dodge Taxes and How to Make Them Pay. W. W. Norton.
2. Zucman, G. (2015). The Hidden Wealth of Nations: The Scourge of Tax Havens. University of Chicago Press. DOI: 10.7208/chicago/9780226245560.001.0001
3. Diamond, P., & Saez, E. (2011). The case for a progressive tax: From basic research to policy recommendations. Journal of Economic Perspectives, 25(4), 165-190. DOI: 10.1257/jep.25.4.165
4. Congressional Budget Office. (2023). The Distribution of Household Income, 2020. View source
5. Congressional Budget Office. (2018). The Budget and Economic Outlook: 2018 to 2028. View source
6. Mirrlees, J. A. (1971). An exploration in the theory of optimum income taxation. Review of Economic Studies, 38(2), 175-208. DOI: 10.2307/2296779
7. Atkinson, A. B., & Stiglitz, J. E. (1976). The design of tax structure: Direct versus indirect taxation. Journal of Public Economics, 6(1-2), 55-75. DOI: 10.1016/0047-2727(76)90041-4
8. OECD. (2021). Tax Challenges Arising from the Digitalisation of the Economy - Global Anti-Base Erosion Model Rules (Pillar Two). OECD/G20 Inclusive Framework on BEPS. DOI: 10.1787/782bac33-en
9. Chetty, R., Friedman, J. N., & Rockoff, J. (2011). New Evidence on the Long-Term Impacts of Tax Credits. National Bureau of Economic Research Working Paper 17699.
10. Joint Committee on Taxation. (2021). Present Law and Background on Tax Treatment of Investment Fund Managers. JCX-22-21.
11. Piketty, T. (2014). Capital in the Twenty-First Century. (A. Goldhammer, Trans.). Harvard University Press.