Federal Income Tax Calculator (Single)

This authoritative, mobile‑first tool estimates U.S. federal income tax for single filers. Enter your income, optional pre‑tax adjustments, choose standard or itemized deductions, and instantly view your taxable income, federal tax, marginal and effective rates, and an estimated refund or amount due.

Calculator

Calculations use official IRS brackets and the standard deduction for the selected year.
This tool is dedicated to Single filers.
Your total income before taxes and deductions. Do not include employer-paid amounts not in your wages.
Above-the-line deductions reduce Adjusted Gross Income (AGI). This field aggregates eligible contributions and adjustments.
Deduction method
If Itemized is selected, enter your total itemized amount below.

Results

Adjusted Gross Income (AGI) $0
Deduction applied $0
Taxable income $0
Estimated federal income tax $0
Less nonrefundable credits − $0
Final federal income tax $0
Effective tax rate 0%
Marginal tax rate 0%
After-tax income $0
Estimated refund / amount due $0

Data Source and Methodology

Primary authoritative sources:

Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.

The Formula Explained

$$\mathrm{AGI} = \max\{0,\ \mathrm{Gross\ Income} - \mathrm{Pre\text{-}tax\ Adjustments}\}$$ $$D = \begin{cases} \mathrm{Standard\ Deduction}(y,\ \mathrm{Single}) & \text{if standard is chosen} \\ \max\{0,\ \mathrm{Itemized}\} & \text{if itemized is chosen} \end{cases}$$ $$\mathrm{Taxable\ Income}\ (TI) = \max\{0,\ \mathrm{AGI} - D\}$$ $$T = \sum_i r_i \cdot \min\{\max(TI - L_i,\ 0),\ U_i - L_i\}$$ $$T_{\mathrm{final}} = \max\{0,\ T - C_{\mathrm{nonref}}\}$$ $$\mathrm{Effective\ Rate} = \frac{T_{\mathrm{final}}}{\mathrm{Gross\ Income}} \quad\quad \mathrm{Marginal\ Rate} = r_j \text{ for bracket } j \text{ where } TI \in (L_j, U_j]$$

Where r is the bracket rate, and L/U are the lower/upper bounds for each IRS bracket for the selected year.

Glossary of Variables

How It Works: A Step‑by‑Step Example

Inputs (Single, 2025): Gross income = $85,000; Pre‑tax adjustments = $5,000; Deduction = Standard (Single 2025: $15,300); Credits = $0; Withholding = $8,000.

  1. AGI = $85,000 − $5,000 = $80,000.
  2. Taxable income = $80,000 − $15,300 = $64,700.
  3. Apply 2025 brackets (Single): 10% up to $11,900; 12% $11,900–$48,550; 22% $48,550–$103,350; higher brackets not reached.
  4. Tax = 10% × 11,900 ($1,190) + 12% × 36,650 ($4,398) + 22% × 16,150 ($3,553) = $9,141.
  5. Final federal income tax = $9,141 − $0 = $9,141. Effective rate ≈ $9,141 / $85,000 = 10.76%. Marginal rate = 22%.
  6. Withholding comparison: $8,000 withheld → amount due ≈ $1,141.

Frequently Asked Questions (FAQ)

Does this calculator include FICA (Social Security and Medicare)?

No. It estimates federal income tax only. Payroll taxes (FICA), state/local taxes, AMT, NIIT, and complex phase‑outs are outside scope.

Which tax years are supported?

2024 and 2025 for Single filers, using IRS inflation‑adjusted brackets and the standard deduction for each year.

Can I enter itemized deductions?

Yes. Choose Itemized and provide your total. The calculator uses that amount as your deduction instead of the standard deduction.

What credits are supported?

A total for nonrefundable credits. Specific credits with eligibility rules (e.g., AOTC, Saver’s Credit) are not calculated individually.

What’s the difference between effective and marginal rate?

Marginal is the rate on your last dollar of taxable income; effective is your total federal tax divided by gross income.

Is this a substitute for professional advice?

No. It’s an educational estimate. Consult a qualified tax professional for personalized guidance.

Tool developed by Ugo Candido. Content verified by the CalcDomain Editorial Team.
Last reviewed for accuracy on: .