Estimate your federal income tax, Social Security, and Medicare withholdings.
Weekly
Bi-Weekly
Monthly
Semi-Monthly
Annually
Single
Married Filing Jointly
Married Filing Separately
Head of Household
Understanding Payroll Withholding
Payroll withholding is the process by which an employer deducts amounts from an employee's gross pay to remit to government agencies and for other authorized purposes. The primary withholdings are federal income tax, Social Security tax, and Medicare tax. Understanding how these are calculated can help you better estimate your net pay and manage your finances.
Federal Income Tax Withholding
Federal income tax withholding is calculated based on the information provided on your Form W-4, Employee's Withholding Certificate. The key factors are:
Gross Pay: Your total earnings before any deductions.
Pay Frequency: How often you are paid (weekly, bi-weekly, monthly, etc.).
Filing Status: Whether you are single, married filing jointly, married filing separately, or head of household. This affects the tax brackets and standard deduction used in calculations.
Number of Allowances: Each allowance you claim effectively reduces the amount of income subject to withholding. More allowances mean less tax withheld.
Additional Withholding: If you elect to have extra tax withheld, this amount is added to your total withholding.
Employers use wage bracket methods or percentage methods, often referencing IRS Publication 15-T, Federal Income Tax Withholding Methods, to determine the correct amount to withhold. For simplicity in this calculator, we use a common approximation based on annualizing income and applying a simplified tax bracket structure. Please note that actual withholding might vary slightly based on the employer's specific method and the most current IRS guidelines.
Social Security and Medicare Taxes (FICA)
These are often referred to as FICA taxes (Federal Insurance Contributions Act). They are calculated at a flat rate:
Social Security Tax: 6.2% on earnings up to an annual wage base limit ($168,600 for 2024).
Medicare Tax: 1.45% on all earnings, with no wage limit. Additional Medicare tax of 0.9% applies to earnings over $200,000 (for single filers) or $250,000 (for married filing jointly).
This calculator provides an estimate for federal income tax, Social Security, and Medicare. It does not include state or local income taxes, or other potential deductions like health insurance premiums, retirement contributions, or wage garnishments.
How the Calculator Works (Simplified)
This calculator aims to provide a reasonable estimate. The core logic involves:
Annualizing the gross pay based on the pay frequency.
Adjusting the annualized gross pay based on the number of allowances claimed (a simplified deduction).
Calculating the estimated annual federal income tax using simplified tax brackets.
Converting the estimated annual federal income tax back to a per-pay-period withholding amount.
Calculating Social Security tax (6.2% up to the wage limit).
Calculating Medicare tax (1.45%).
Adding any specified additional annual withholding, then dividing by the number of pay periods.
Disclaimer: This calculator is for informational purposes only and does not constitute financial or tax advice. Consult with a qualified tax professional for advice specific to your situation.
function calculateWithholding() {
var grossPay = parseFloat(document.getElementById("grossPay").value);
var payFrequency = parseInt(document.getElementById("payFrequency").value);
var filingStatus = document.getElementById("filingStatus").value;
var allowances = parseInt(document.getElementById("allowances").value);
var additionalWithholding = parseFloat(document.getElementById("additionalWithholding").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = "";
if (isNaN(grossPay) || grossPay < 0) {
resultDiv.innerHTML = "Please enter a valid gross pay amount.";
return;
}
if (isNaN(allowances) || allowances < 0) {
resultDiv.innerHTML = "Please enter a valid number of allowances.";
return;
}
if (isNaN(additionalWithholding) || additionalWithholding < 0) {
resultDiv.innerHTML = "Please enter a valid additional withholding amount.";
return;
}
// — Constants and Simplified Tax Brackets (Example for 2024, adjust as needed) —
var annualWageBaseLimitSS = 168600;
var ficaTaxRateSS = 0.062; // Social Security
var ficaTaxRateMedicare = 0.0145; // Medicare
var additionalMedicareTaxRate = 0.009;
var additionalMedicareThresholdSingle = 200000;
var additionalMedicareThresholdMFJ = 250000;
var additionalMedicareThresholdMS = 125000; // For Married Filing Separately
// Simplified tax brackets – these are highly simplified for demonstration
// In reality, these vary significantly and depend on the specific tax year and IRS tables.
// These are NOT exact IRS brackets.
var taxBrackets = {
single: [
{ limit: 11600, rate: 0.10 },
{ limit: 47150, rate: 0.12 },
{ limit: 100525, rate: 0.22 },
{ limit: 191950, rate: 0.24 },
{ limit: 243725, rate: 0.32 },
{ limit: 609350, rate: 0.35 },
{ limit: Infinity, rate: 0.37 }
],
married_jointly: [
{ limit: 23200, rate: 0.10 },
{ limit: 94300, rate: 0.12 },
{ limit: 201050, rate: 0.22 },
{ limit: 383900, rate: 0.24 },
{ limit: 487450, rate: 0.32 },
{ limit: 1218700, rate: 0.35 },
{ limit: Infinity, rate: 0.37 }
],
married_separately: [
{ limit: 11600, rate: 0.10 },
{ limit: 47150, rate: 0.12 },
{ limit: 100525, rate: 0.22 },
{ limit: 191950, rate: 0.24 },
{ limit: 243725, rate: 0.32 },
{ limit: 609350, rate: 0.35 },
{ limit: Infinity, rate: 0.37 }
],
head_of_household: [
{ limit: 16550, rate: 0.10 },
{ limit: 63100, rate: 0.12 },
{ limit: 132750, rate: 0.22 },
{ limit: 207800, rate: 0.24 },
{ limit: 261500, rate: 0.32 },
{ limit: 553850, rate: 0.35 },
{ limit: Infinity, rate: 0.37 }
]
};
// Adjustments based on allowances (simplified model: each allowance reduces taxable income by a fixed amount per pay period, annualized)
// This is a rough approximation. Real W-4 calculations are more complex.
var allowanceValueAnnual = 4700; // Example value for 2024, varies.
var totalAnnualAllowanceReduction = allowances * allowanceValueAnnual;
// 1. Annualize Gross Pay
var grossAnnualPay = grossPay * payFrequency;
// 2. Apply Allowance Reduction and Additional Withholding (Annualized)
var taxableAnnualIncome = grossAnnualPay – totalAnnualAllowanceReduction;
taxableAnnualIncome = Math.max(0, taxableAnnualIncome); // Ensure taxable income is not negative
var totalAnnualTaxWithholding = 0;
// 3. Calculate Estimated Federal Income Tax (Using simplified brackets)
var incomeForFederalTax = taxableAnnualIncome;
var federalTaxWithholdingAnnual = 0;
var brackets = taxBrackets[filingStatus];
var previousLimit = 0;
if (brackets) {
for (var i = 0; i previousLimit) {
taxableAmountInBracket = Math.min(incomeForFederalTax, bracket.limit) – previousLimit;
federalTaxWithholdingAnnual += taxableAmountInBracket * bracket.rate;
}
previousLimit = bracket.limit;
if (incomeForFederalTax medicareThreshold) {
additionalMedicareTaxAnnual = (grossAnnualPay – medicareThreshold) * additionalMedicareTaxRate;
}
var medicareTaxTotalAnnual = medicareTaxAnnual + additionalMedicareTaxAnnual;
var medicareTaxPerPeriod = medicareTaxTotalAnnual / payFrequency;
// Display Results
var estimatedFederalTaxPerPeriodFormatted = estimatedFederalTaxPerPeriod.toFixed(2);
var socialSecurityTaxPerPeriodFormatted = socialSecurityTaxPerPeriod.toFixed(2);
var medicareTaxPerPeriodFormatted = medicareTaxPerPeriod.toFixed(2);
var totalWithholdingPerPeriod = estimatedFederalTaxPerPeriod + socialSecurityTaxPerPeriod + medicareTaxPerPeriod;
var netPayPerPeriod = grossPay – totalWithholdingPerPeriod;
resultDiv.innerHTML = `
Estimated Net Pay: $${netPayPerPeriod.toFixed(2)}
Estimated Federal Income Tax: $${estimatedFederalTaxPerPeriodFormatted}
Estimated Social Security Tax: $${socialSecurityTaxPerPeriodFormatted}