Federal Revenue

The single largest source of federal revenue, graduated so that higher incomes face higher marginal rates. Collections rise and fall with the economy and with changes to rates, brackets, deductions and credits.

Dedicated taxes on wages that fund Social Security and Medicare. They are regressive relative to income because they apply only up to a wage cap for Social Security, but they provide a stable, large revenue stream.

Taxes on business profits. They are a smaller and more volatile share of revenue than in past decades, sensitive to profitability, the business cycle and changes to the tax code.

Excise taxes on specific goods (fuel, alcohol, tobacco), customs duties on imports, estate and gift taxes, and miscellaneous fees and receipts. Together these are a modest but meaningful portion of the total.