Tax Withholding & Refund Estimator
Estimate your federal income tax liability based on your gross income, filing status, deductions, and credits — then compare it to your year-to-date withholding to project your refund or balance due.
Formulas Used
1. Total Gross Income
Total Gross = W-2 / Salary Income + Other Taxable Income
2. Adjusted Gross Income (AGI)
AGI = Total Gross Income − Above-the-Line Adjustments
(IRA deductions, student loan interest, HSA contributions, etc.)
3. Taxable Income
Taxable Income = AGI − max(Standard Deduction, Itemized Deductions)
4. Gross Tax Liability (Progressive Brackets)
Tax = Σ [ ratei × (min(Taxable Income, Bracketi upper) − Bracketi lower) ]
for each bracket i where Taxable Income > Bracketi lower
5. Net Tax After Credits
Net Tax = max(0, Gross Tax − Non-Refundable Credits)
6. Refund / Amount Owed
Balance = (Federal Withholding + Other Payments) − Net Tax
Positive balance → Refund | Negative balance → Amount Owed
7. Effective Tax Rate
Effective Rate = Net Tax ÷ Taxable Income × 100
Assumptions & References
- Uses 2024 tax year parameters per IRS Rev. Proc. 2023-34 and IRS Publication 505.
- Standard deductions (2024): Single $14,600 | MFJ $29,200 | MFS $14,600 | Head of Household $21,900.
- Seven federal income tax brackets: 10%, 12%, 22%, 24%, 32%, 35%, 37%.
- Credits are treated as non-refundable (reduce tax to $0 minimum). Refundable credits (e.g., EITC, Additional Child Tax Credit) are not modeled separately.
- Does not include: Alternative Minimum Tax (AMT), Net Investment Income Tax (NIIT), self-employment tax, state/local income taxes, or the Additional Medicare Tax (0.9%).
- Above-the-line adjustments include but are not limited to: traditional IRA deductions (up to $7,000 / $8,000 if 50+), student loan interest (up to $2,500), HSA contributions, and alimony (pre-2019 agreements).
- This tool is for estimation purposes only and does not constitute tax advice. Consult a qualified tax professional or use the official IRS Tax Withholding Estimator at irs.gov.
- References: IRS Publication 505 (Tax Withholding and Estimated Tax), IRS Publication 17 (Your Federal Income Tax), IRS Rev. Proc. 2023-34.