How Federal Tax Calculation Works
The United States uses a progressive tax system, which means different portions of your income are taxed at different rates. Our calculator applies this method in four steps.
Step 1: Determine Gross Income. We start with your total annual income from all sources, including wages (W-2), self-employment income (1099), investment income, Social Security benefits, and other taxable income.
Step 2: Apply Deductions. We subtract either the standard deduction for your filing status or your itemized deductions, whichever is greater. For the 2025 tax year (filed in 2026), the standard deduction is $15,000 for single filers, $30,000 for married filing jointly, $15,000 for married filing separately, and $22,500 for head of household. The result is your taxable income.
Step 3: Calculate Tax Using Progressive Brackets. Your taxable income is divided into portions that fall within each bracket. For example, a single filer with $60,000 in taxable income would pay 10% on the first $11,925 ($1,192.50), then 12% on the amount from $11,925 to $48,475 ($4,386), then 22% on the amount from $48,475 to $60,000 ($2,535.50), for a total federal tax of $8,114. This is your tax before credits.
Step 4: Apply Credits and Withholding. We subtract any tax credits you qualify for (such as the Child Tax Credit, Earned Income Tax Credit, or education credits) from your tax before credits. Then we compare the resulting total tax to the amount already withheld from your paychecks or paid through estimated payments. If you paid more than you owe, you get a refund. If you paid less, you owe the difference.
State Tax Calculation
State tax calculations follow similar progressive bracket logic but use each state's published bracket rates and deduction amounts. Some states like Illinois and Pennsylvania use a flat tax rate, where all income is taxed at the same percentage. States like Texas, Florida, and Nevada have no state income tax at all. Our state calculators account for these differences and use state-specific data from each state's department of revenue.
Self-Employment Tax
Self-employed individuals pay an additional self-employment (SE) tax that covers Social Security and Medicare contributions. Our freelancer calculator computes SE tax by first multiplying net self-employment income by 92.35% (the taxable portion), then applying 12.4% for Social Security on income up to the wage base limit ($176,100 for 2025) and 2.9% for Medicare on all income, plus an additional 0.9% Medicare surtax on income above $200,000. Half of the SE tax is deductible as an above-the-line deduction, which our calculator automatically factors in.
Data Sources
Our calculations use data from the following official sources. For federal brackets and standard deductions, we use IRS Revenue Procedure 2024-40 (for 2025 tax year) and projected 2026 figures based on IRS inflation adjustment methodology. For state brackets, we reference each state's department of revenue published rates, updated annually. Self-employment tax rates and thresholds come from IRS Publication 15 and IRS Topic No. 554. Credit amounts and eligibility rules are sourced from IRS Publication 17 and individual credit-specific publications.
Limitations
Our calculators provide estimates based on general tax rules and the information you provide. They do not account for the Alternative Minimum Tax (AMT), foreign tax credits or foreign earned income exclusion, complex investment income scenarios such as wash sales or cryptocurrency, Net Investment Income Tax (NIIT), certain less common credits and deductions, or amended returns or carryforward amounts. For complex tax situations, we recommend consulting a qualified tax professional.
Accuracy Commitment
We regularly test our calculators against IRS tax tables and professional tax software to ensure accuracy. When the IRS publishes updated rates, brackets, or credit amounts, we update our calculators within 72 hours. All updates are logged with a visible "Last updated" date on each page.