Simple Tax Calculator
Estimate tax amount, marginal rate, and effective rate with a simplified input model.
Tax Planning · Last reviewed: August 9, 2026
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Overview
The Simple Tax Calculator estimates federal income tax by applying the selected tax year’s standard deduction and ordinary-income tax brackets to the entered annual income. It reports estimated tax, the marginal bracket rate reached, and tax as a percentage of gross income.
This deliberately narrow model is useful for a quick baseline, not for preparing a tax return or estimating a person’s complete federal tax liability.
Scope and Use
Use the estimate for simple comparisons when gross annual income, one filing status, the standard deduction, and ordinary-income brackets are an appropriate approximation. The selected year determines both the deduction and bracket schedule.
Outside this model
- Itemized deductions and deductions beyond the standard deduction.
- Tax credits, dependents, withholding, estimated payments, and refunds.
- Preferential rates for qualified dividends or long-term capital gains.
- Self-employment, payroll, alternative minimum, net investment income, additional Medicare, state, and local taxes.
- Income adjustments, phaseouts, special elections, and other return-specific rules.
Inputs and Outputs
Labels and ordering follow the active Simple Tax calculator configuration. The calculator has no overridable assumptions.
| Field | Format | Meaning | Interpretation |
|---|---|---|---|
| Annual incomeinput | Currency | Gross annual income treated entirely as income subject to the ordinary federal rate schedule. | This is not taxable income or adjusted gross income. The calculator subtracts only the selected standard deduction. |
| Tax yearinput | Tax year selection | The governed federal standard deduction and ordinary-income bracket schedule used for the estimate. | — |
| Filing statusinput | Filing status selection | The filing status used to select the governed standard deduction and bracket schedule. | — |
| Estimated federal taxoutput | Currency | Estimated federal tax after the standard deduction and progressive ordinary-income brackets are applied. | Rounded to the nearest whole dollar using half-up rounding. |
| Marginal rateoutput | Percentage | The rate of the highest bracket containing taxable income, not the rate applied to all income. | Returns 0% when taxable income is zero. |
| Effective rateoutput | Percentage | The unrounded estimated tax divided by entered gross annual income. | Displayed to two decimal places. |
- Field
- Annual incomeinput
- Format
- Currency
- Meaning
- Gross annual income treated entirely as income subject to the ordinary federal rate schedule.
- Interpretation
- This is not taxable income or adjusted gross income. The calculator subtracts only the selected standard deduction.
- Field
- Tax yearinput
- Format
- Tax year selection
- Meaning
- The governed federal standard deduction and ordinary-income bracket schedule used for the estimate.
- Interpretation
- —
- Field
- Filing statusinput
- Format
- Filing status selection
- Meaning
- The filing status used to select the governed standard deduction and bracket schedule.
- Interpretation
- —
- Field
- Estimated federal taxoutput
- Format
- Currency
- Meaning
- Estimated federal tax after the standard deduction and progressive ordinary-income brackets are applied.
- Interpretation
- Rounded to the nearest whole dollar using half-up rounding.
- Field
- Marginal rateoutput
- Format
- Percentage
- Meaning
- The rate of the highest bracket containing taxable income, not the rate applied to all income.
- Interpretation
- Returns 0% when taxable income is zero.
- Field
- Effective rateoutput
- Format
- Percentage
- Meaning
- The unrounded estimated tax divided by entered gross annual income.
- Interpretation
- Displayed to two decimal places.
Methodology
The calculator selects the standard deduction and bracket table for the entered year and filing status. Taxable income cannot fall below zero.
Here TI is taxable income, GI is entered gross annual income, and SD is the governed standard deduction for the selected year and filing status.
Taxable income is then allocated across the progressive bracket tiers. Each occupied tier is measured from the preceding bracket ceiling, so the schedule remains continuous at a boundary. Each tier amount is multiplied by that tier’s rate and the results are summed.
For each occupied bracket i, A is the taxable amount in that bracket and r is its rate. Only the final tax output is rounded to a whole dollar.
The marginal-rate output is the rate of the highest occupied bracket. When taxable income is zero, estimated tax and both reported rates are zero. The effective rate divides the unrounded tax by gross income; both rate outputs are converted to percentages and rounded to two decimals.
Assumptions and Limitations
Model assumptions
- All entered income is treated as ordinary gross income.
- The selected filing status applies for the full tax year.
- Only the standard deduction reduces entered income.
- The governed year-specific schedule is applicable to the scenario.
Limitations
- The result is not a tax return or comprehensive tax projection.
- It does not determine eligibility for deductions or credits.
- It does not separate income by character or source.
- It does not calculate payments, balances due, or refunds.
Selected Sources
- Internal Revenue Bulletin 2025-45: Revenue Procedure 2025-32
Internal Revenue Service · Published November 10, 2025 · Retrieved August 9, 2026
The governed federal standard deductions and ordinary-income bracket schedules used by the simplified model. It does not support a user-specific tax estimate or the exclusion of return-specific rules.
Supported calculator tax years