The marginal tax rate is what you pay on your highest dollar of taxable income. The U.S. progressive marginal tax method means one pays more tax as income grows.

Marginal tax rate is the rate you pay on your last dollar of income, based on your tax bracket. Effective tax rate is the average rate you pay on all of your income. Understanding the difference is ...

Kelsey Plum doesn't understand marginal tax rates, but the topic trips up even tax experts.