Calculating the exact federal income tax on $1,000,000 requires applying progressive marginal tax brackets, meaning different portions of income are taxed at incremental rates ranging from 10 percent up to the maximum top marginal rate of 37 percent for high earners. Because of this bracketed structure, the effective tax rate is lower than the top marginal rate, resulting in a total federal income tax liability that depends on deductions, credits, and filing status.