How a Flat Tax Works
Under a flat tax, you multiply your taxable income by a single rate. Taxable income is the income left after you subtract deductions, which are amounts the tax code lets you take off your total income.
Because there’s only one rate, two people with different incomes pay the same percentage. The person who earns more still pays more in dollars, but neither pays a higher rate on extra income.
Flat Tax vs. Progressive Federal Income Tax
The 2026 Federal Tax Brackets
For 2026, the IRS tax inflation adjustments set seven federal rates: 10%, 12%, 22%, 24%, 32%, 35%, and 37%. If you file single, the 10% rate applies to taxable income of $12,400 or less ($24,800 for married couples filing jointly). The top 37% rate starts above $640,600 for single filers ($768,700 for joint filers).
Under these federal income tax brackets, moving into a higher bracket doesn’t raise the tax on all your income. You pay the higher rate only on the part that falls in the new bracket. That layering is the core of how tax brackets work, and it’s the main difference from a flat tax.
Example With $60,000 of Taxable Income
Here’s the 2026 math for a single filer with $60,000 of taxable income.
| Portion of income | Rate | Tax |
|---|---|---|
| First $12,400 | 10% | $1,240 |
| Next $38,000 | 12% | $4,560 |
| Remaining $9,600 | 22% | $2,112 |
| Total | $7,912 |
Your federal tax would be $7,912, or about 13.2% of your taxable income. That percentage is your effective tax rate. Now compare it with a hypothetical flat tax of 15%, used here only for illustration.
| System | Tax on $60,000 | Share of taxable income |
|---|---|---|
| 2026 progressive brackets | $7,912 | About 13.2% |
| Hypothetical 15% flat tax | $9,000 | 15% |
Flat Taxes You Already Pay
Social Security and Medicare Taxes
Payroll taxes are a common flat-rate example. Under current Social Security withholding rates, you and your employer each pay 6.2% (12.4% total). For Medicare, you each pay 1.45% (2.9% total).
Social Security tax applies only up to the 2026 wage base of $184,500. Medicare has no wage base limit. Your employer collects both through withholding, which means taking tax out of your pay before you receive it. These flat payroll taxes are part of how much tax comes out of each paycheck.
State Income Taxes
Some states use one flat income tax rate, while others use brackets like the federal system. Nine states have no broad-based individual income tax, so check whether your state has individual income tax before you plan your return.
Pros and Cons of a Flat Tax
Simpler to Calculate
With one rate, you can figure out your tax with a single multiplication.
Concerns About Fairness
Critics say a flat tax shifts more of the burden to lower earners. Everyone pays the same percentage, so a household with less income gives up the same share of each dollar as a high earner.
How Deductions Change the Picture
Deductions can make a flat tax partly progressive in effect. The federal system already offers a 2026 standard deduction of $16,100 for single filers. If a flat tax kept a deduction like that, the first part of everyone’s income would go untaxed. Lower earners would then pay a smaller share of their total income.
