Estimate your net pay in Illinois after federal, state, and FICA taxes.
Weekly
Bi-Weekly
Semi-Monthly
Monthly
Estimated Net Pay
$0.00 (Your estimated take-home pay)
Understanding Your Illinois Paycheck
This calculator helps you estimate your net pay (take-home pay) based on your gross earnings and various deductions in Illinois. Understanding these deductions is crucial for financial planning.
Key Deductions Calculated:
Federal Income Tax: Calculated based on your gross pay, pay frequency, and the number of federal allowances you claim on your W-4 form. Higher allowances generally mean lower withholding.
FICA Taxes (Social Security & Medicare): These are federal taxes that fund Social Security and Medicare programs.
Social Security: 6.2% on earnings up to an annual limit (this calculator uses the standard limit for the current year).
Medicare: 1.45% on all earnings, with no income limit.
Illinois State Income Tax: Illinois has a flat income tax rate. This calculator applies the current flat rate (currently 4.95%) to your taxable income after considering your Illinois W-4 allowances and pre-tax deductions.
Pre-Tax Deductions: Contributions to certain benefits like health insurance premiums and retirement plans (like 401(k)) are typically deducted before income taxes are calculated, reducing your taxable income and thus your tax liability.
Federal Income Tax Withholding: This is a complex calculation involving IRS tax tables, which depend on your filing status, pay frequency, and allowances. For simplicity, this calculator uses an approximation based on standard withholding percentages and allowances. Note: For precise federal withholding, consult IRS resources or your employer's payroll system.
FICA Taxes: Calculated directly on your gross pay (subject to the Social Security wage base limit).
Illinois State Income Tax: Illinois State Tax Rate (4.95%) * (Adjusted Gross Income (Illinois) – Illinois Allowances * Standard Exemption Amount). The standard exemption amount per allowance for Illinois is updated annually.
Net Pay: Gross Pay – Federal Income Tax – FICA Taxes – Illinois State Income Tax – Any other post-tax deductions (not included in this basic calculator).
Disclaimer:
This calculator provides an estimation only. Actual net pay may vary due to factors not included, such as local taxes, additional FICA taxes (Additional Medicare Tax), specific W-4/IL-W-4 elections (like additional withholding amounts), union dues, wage garnishments, or other voluntary/involuntary deductions. For an exact figure, please refer to your official pay stub or consult your employer's HR/Payroll department.
function calculateIllinoisPaycheck() {
var grossPay = parseFloat(document.getElementById("grossPay").value) || 0;
var payFrequency = document.getElementById("payFrequency").value;
var federalAllowances = parseInt(document.getElementById("federalAllowances").value) || 0;
var stateAllowances = parseInt(document.getElementById("stateAllowances").value) || 0;
var healthInsurance = parseFloat(document.getElementById("healthInsurance").value) || 0;
var retirementContributions = parseFloat(document.getElementById("retirementContributions").value) || 0;
var resultElement = document.getElementById("calculationResult");
// — Constants and Assumptions —
var FEDERAL_INCOME_TAX_RATE_APPROX = 0.15; // Simplified federal rate for estimation
var SOCIAL_SECURITY_RATE = 0.062;
var MEDICARE_RATE = 0.0145;
var ILLINOIS_STATE_TAX_RATE = 0.0495; // As of current Illinois flat tax rate
var SOCIAL_SECURITY_WAGE_BASE = 168600; // Standard SS wage base for 2024 (update annually if needed)
var ILLINOIS_EXEMPTION_PER_ALLOWANCE = 2425; // Standard exemption amount per allowance for IL (update annually if needed)
// — Adjustments for Pay Frequency —
var annualGrossPay = grossPay;
if (payFrequency === "weekly") {
annualGrossPay = grossPay * 52;
} else if (payFrequency === "bi-weekly") {
annualGrossPay = grossPay * 26;
} else if (payFrequency === "semi-monthly") {
annualGrossPay = grossPay * 24;
} else if (payFrequency === "monthly") {
annualGrossPay = grossPay * 12;
}
// — Calculate Pre-Tax Deductions —
var totalPreTaxDeductions = healthInsurance + retirementContributions;
// Ensure pre-tax deductions don't exceed gross pay for taxability calculation
if (totalPreTaxDeductions > grossPay) {
totalPreTaxDeductions = grossPay;
}
// — Calculate Taxable Income —
var federalTaxableIncome = grossPay – totalPreTaxDeductions;
var stateTaxableIncome = grossPay – totalPreTaxDeductions;
// — Calculate Federal Income Tax Withholding (Simplified Approximation) —
// This is a very basic estimation. Real calculation uses tax brackets and tables.
var estimatedFederalTax = federalTaxableIncome * FEDERAL_INCOME_TAX_RATE_APPROX;
// Adjust for allowances (very rough approximation)
var allowanceAdjustmentFederal = federalAllowances * 1000 / (payFrequency === "weekly" ? 52 : (payFrequency === "bi-weekly" ? 26 : (payFrequency === "semi-monthly" ? 24 : 12)));
estimatedFederalTax = Math.max(0, estimatedFederalTax – allowanceAdjustmentFederal);
// — Calculate FICA Taxes —
var socialSecurityTax = Math.min(grossPay * SOCIAL_SECURITY_RATE, SOCIAL_SECURITY_WAGE_BASE * SOCIAL_SECURITY_RATE);
var medicareTax = grossPay * MEDICARE_RATE;
var ficaTaxes = socialSecurityTax + medicareTax;
// — Calculate Illinois State Income Tax —
var stateTaxableIncomeAfterExemptions = stateTaxableIncome – (stateAllowances * ILLINOIS_EXEMPTION_PER_ALLOWANCE / (payFrequency === "weekly" ? 52 : (payFrequency === "bi-weekly" ? 26 : (payFrequency === "semi-monthly" ? 24 : 12))));
var illinoisStateTax = Math.max(0, stateTaxableIncomeAfterExemptions * ILLINOIS_STATE_TAX_RATE);
// — Calculate Net Pay —
var netPay = grossPay – estimatedFederalTax – ficaTaxes – illinoisStateTax;
// Ensure net pay is not negative
netPay = Math.max(0, netPay);
// — Format and Display Result —
resultElement.innerHTML = "$" + netPay.toFixed(2) + " (Your estimated take-home pay)";
}
// Initial calculation on page load
window.onload = calculateIllinoisPaycheck;