Marginal Tax Rate: What It Is and How to Calculate It, With Examples

What Is a Marginal Tax Rate?

The marginal tax rate is the tax rate you pay on an additional dollar of income. In the United States, the federal marginal tax rate for individuals increases as income rises. This means that your marginal tax rate will likely be lower than your tax bracket.

This method of taxation, known as progressive taxation, aims to tax individuals based upon their earnings, with low-income earners being taxed at a lower rate than higher-income earners.

Understanding Marginal Tax Rate

Under a marginal tax rate, taxpayers are most often divided into tax brackets or ranges, which determine the rate applied to the taxable income of the tax filer. As income increases, the last dollar earned will be taxed at a higher rate than the first dollar earned. In other words, the first dollar earned will be taxed at the rate for the lowest tax bracket, the last dollar earned will be taxed at the rate of the highest bracket for that total income, and all the money in between is taxed at the rate for the range into which it falls.

Marginal tax rates can be changed by new tax laws. The current marginal tax rates went into effect in the United States as of Jan. 1, 2018, with the passage of the Tax Cuts and Jobs Act (TCJA). Under the previous law, the seven brackets were 10%, 15%, 25%, 28%, 33%, 35%, and 39.6%. The new plan, signed into law in Dec. 2017, keeps the seven bracket structure. However, adjustments were made to the tax rates and income levels.

Under the TCJA, the new rates are 10%, 12%, 22%, 24%, 32%, 35%, and 37%.

Marginal vs. Flat Tax

The other type of tax rate is the flat tax rate, which a few states implement for state income tax. Under this system of taxation, people aren’t taxed on a scale (like the marginal tax rate), but rather, flat across the board. In other words, everyone is charged the same rate, regardless of income level.

Most systems that use a flat tax rate do not allow for deductions and are seen in countries with a rising economy. Those who support this system of taxation describe it as fair, as it taxes all people and businesses at the same rate. Those who oppose it believe that it results in high-income taxpayers paying less than they should for an equitable society.

Marginal Tax Rate Example

The table below shows the rates and income levels for three types of filer in 2022: single, married filing jointly, and heads of household.

Individuals who make the lowest amount of income are placed into the lowest marginal tax rate bracket, while higher-earning individuals are placed into higher marginal tax brackets. However, the marginal tax bracket in which an individual falls does not determine how the entire income is taxed. Instead, income taxes are assessed progressively, with each bracket having a range of income values that are taxed at a particular rate. 

Under the current plan, if a single taxpayer earned $150,000 in taxable income, they would owe the following income taxes for 2022 (due in April 2023), as shown below:

• 10% Bracket: ($10,275 - $0) x 10% = $1,027.50
• 12% Bracket: ($41,775 - $10,275) x 12% = $3,780.00
• 22% Bracket: ($89,075 - $41,775) x 22% = $10,406.00
• 24% Bracket: ($150,000 - $89,075) x 24% = $14,622.00
• 32% Bracket: Not applicable
• 35% Bracket: Not applicable
• 37% Bracket: Not applicable

If you add up these amounts, the entire tax liability for this individual would be $3\29,835.50, or an effective tax rate of 19.9% = ($29,835.50 / $150,000).

The seven marginal tax rates of the brackets remain constant regardless of a person's filing status. However, the dollar ranges at which income is taxed at each rate change depending on whether the filer is a single person, a married joint filer, or a head-of-household filer. In addition, due to a provision in the tax code referred to as indexing, the dollar range of each marginal tax bracket typically increases annually to account for inflation.

The Bottom Line

The U.S. has a marginal tax rate system, whereby different tax brackets (with ever-increasing tax rates) kick in at different levels of income. This means that you are taxed at a certain rate for certain amounts of income that progressively get larger. So, if you make $1,000,000 a year and the tax bracket for that amount is 37%, you will not pay that percent on all one million dollars. Instead you will pay marginal rates for each tax bracket up to $539,900 of income (for single filers). Only the last $460,100 would be subject to the 37% rate.