Methodology.

The site assembles five annual data series for the United States, 1944 through 2024, and juxtaposes them with current top marginal personal income tax rates from a set of peer countries. Every number shown is drawn from public, audited, government or multilateral sources. Where a value is not yet verified against a primary source, the site's source file tags it [VERIFY] and it will be corrected before the domain cutover.

Series & sources

• Top marginal personal income tax rate — Federal statutory rate applied to the highest bracket. Source: Tax Foundation historical rate tables, cross-checked with IRS Form 1040 instructions for each year.
• Top marginal corporate income tax rate — Federal statutory rate applied to the highest corporate bracket. Source: Tax Foundation historical corporate rate tables.
• Federal revenue as a share of GDP — Total federal receipts (all sources) divided by nominal GDP. Source: Office of Management and Budget, Historical Tables, Table 1.2 and Table 2.3.
• Corporate income tax receipts as a share of GDP — Federal corporate income tax revenue divided by nominal GDP. Source: OMB Historical Tables, Table 2.3, cross-checked with FRED series FCTAX.
• Total federal debt as a share of GDP — Gross federal debt (debt held by the public plus intragovernmental holdings) divided by nominal GDP. Source: FRED series GFDGDPA188S.
• Current top marginal personal rates, peer countries (2024) — National top marginal rate, including sub-national where comparable to US federal rate. Sources: KPMG Individual Income Tax Rates Table, OECD Tax Database, PwC Worldwide Tax Summaries.
• Consumer Price Index (CPI-U, 1982–84 = 100) — Used to convert historical incomes to current dollars for the salary calculator. Source: US Bureau of Labor Statistics, CPI-U annual averages.
• Historical federal income tax brackets (single filer) — Used for the salary calculator. Source: IRS Form 1040 instructions and Tax Foundation historical bracket tables.
• Current nominal GDP and federal deficit — Used in counterfactual revenue math. Sources: Bureau of Economic Analysis and Congressional Budget Office.

Counterfactual math

The "Treasury would collect X more per year" figure is computed as:

(revenue_GDP[year] − revenue_GDP[2024]) × current_nominal_GDP

This is deliberately the simplest possible comparison — it asks what would happen to federal revenue if today's economy produced the same revenue-to-GDP ratio observed in the selected year. It does not attempt to model elasticity of taxable income, behavioral responses, or second-order macroeconomic effects. It assumes the tax structure scales proportionally to GDP, which is how the historical data in this series was itself normalized.

The "enough to" framings that accompany the counterfactual are deliberately rotated for variety, and are computed against current-year reference points: the federal deficit (~$1.83T FY2024), the Pentagon budget (~$850B), federal education spending (~$80B), US household count (~131M), and the NASA budget (~$25B). Sources: CBO, DoD, Department of Education, US Census Bureau, NASA.

Salary calculator

The salary calculator uses federal income tax brackets from ten anchor years — 1944, 1955, 1965, 1975, 1985, 1990, 1995, 2000, 2005, 2010, 2015, 2020, and 2024 — and snaps the slider year to the nearest anchor. Single filer, standard deduction only. No itemized deductions, credits, AMT, payroll tax, state tax, or investment income treatment. It is illustrative, not a tax return. Historical incomes are inflation-adjusted to the slider year's dollars using CPI-U annual averages before the bracket schedule is applied.

Country comparison

The "matches current-day X" line compares the slider year's US top marginal personal rate against the current (2024) top marginal personal rate in roughly thirty peer countries, including most OECD nations. Where the slider year's US rate falls within ±2.5 percentage points of a peer country's current rate, that country is named. Where no peer taxes top earners at the slider year's level, the line reports "No country taxes top earners at this level today." Where the slider year's US rate is lower than most peers — including today's 37% — the line reports that directly.

Scope & limits

The site deliberately focuses on federal statutory rates and aggregate federal receipts. It does not show state or local taxes, payroll taxes (Social Security and Medicare), effective rates paid by specific income groups, capital gains treatment, or sub-national variation within peer countries. Those omissions are not accidents. A site that tried to show everything would show nothing. The purpose here is to highlight a single comparison — federal tax policy then versus now — cleanly.

Readers who want deeper analysis of effective rates by income group are encouraged to consult Saez & Zucman's The Triumph of Injustice, the CBO distributional reports, and the Tax Policy Center.

Errors

If a number on this site is wrong, it should be fixed. Report errors to the site owner; corrections will be dated on this page.