How to Use the US Income Tax Calculator

Before You Start

Gather the records that match the tax year being modeled. Useful documents can include Forms W-2, 1099-INT, 1099-DIV, SSA-1099, business records, estimated-payment confirmations, mortgage-interest records, charitable receipts, and education or dependent-care expenses.

• Filing status and dependent counts
• Each spouse's age, wages, withholding, and estimated payments
• Business, investment, Social Security, passive, and other income
• Potential adjustments, deductions, and credits
• Any optional state and local effective-rate assumption

Step 1: Enter the Tax Year and Filing Status

Enter a supported tax year and choose the federal filing status expected on the return. Filing status changes bracket widths, the standard deduction, capital-gain thresholds, credit phaseouts, and some additional-tax thresholds.

Married filing separately users who enter Social Security benefits must also indicate whether they lived apart from their spouse for the entire year because the modeled taxable-benefit worksheet changes.

Step 2: Enter Income, Withholding, and Payments

Use Form W-2 box 1 for wages and box 5 for Medicare wages. Enter federal, state, and local withholding in their separate fields. Joint filers enter each spouse separately.

Then enter Social Security benefits, tax-exempt interest, taxable interest, ordinary and qualified dividends, passive income, short- and long-term capital gains, and other income. Qualified dividends cannot exceed ordinary dividends.

Step 3: Add Business or Self-Employment Income When Applicable

Select Yes only when net business or self-employment income should be included. The calculator then displays business income, estimated payments, and Medicare-wage fields used by the supported self-employment and Additional Medicare Tax calculations.

On a joint return, each spouse's business income is modeled separately because each spouse generally calculates a separate Schedule SE. W-2 box 1 wages are used as a planning proxy when coordinating the Social Security wage base.

Step 4: Enter Supported Deductions and Credits

Enter only amounts for which eligibility is reasonably expected. The calculator models selected IRA and student-loan adjustments, Schedule 1-A amounts, real-estate tax, mortgage interest, charitable contributions, medical expenses, dependent-care expenses, education expenses, and other entered credits.

The engine compares the modeled standard and itemized deductions and uses the larger result. Medical expenses contribute only above the supported adjusted-gross-income floor, and state and local itemized taxes are subject to the ruleset's modeled cap.

Step 5: Read the Results

1. Adjusted gross income: modeled gross income after supported adjustments.
2. Taxable income: income remaining after supported deductions.
3. Total federal tax: modeled federal income tax plus supported additional taxes after credits.
4. State and local estimate: adjusted gross income multiplied by the effective rate entered.
5. Refund or amount due: estimated tax compared with entered payments and refundable credits.
6. Marginal and effective rates: two different views of the modeled tax burden.

When a state/local rate or withholding is entered, the headline balance is a combined planning result, not the refund shown on a federal Form 1040.

Worked Example: 2026 Single Filer

The default scenario uses a single filer, age 30, with $80,000.00 of W-2 wages and $9,000.00 of federal withholding. With no optional state/local rate, the production engine returns:

The same checked engine values are used on the calculator and Examples pages.

Important Limitations

This calculator does not prepare Form 1040 or model every federal or state rule. It excludes or simplifies items such as alternative minimum tax, qualified business income deduction, earned income credit, marketplace premium tax credit, foreign tax rules, complete capital-loss carryovers, and state-specific returns.

Direct bracket arithmetic can also differ slightly from an IRS tax table used on a filed return. Confirm material decisions with current instructions or a qualified professional.