Weekly
Bi-Weekly (Every 2 weeks)
Semi-Monthly (Twice a month)
Monthly
Single
Married
Head of Household
Estimated Net Pay
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Breakdown
Gross Pay: —
Estimated Taxes: —
Understanding Illinois Payroll and Taxes
Calculating your net pay in Illinois involves understanding various deductions, primarily federal and state income taxes, Social Security, and Medicare. This calculator provides an estimate based on common payroll factors.
How Illinois Payroll is Calculated:
Your take-home pay (net pay) is determined by subtracting all applicable taxes and other deductions from your gross pay. The primary deductions calculated here are:
Federal Income Tax: Calculated based on your gross pay, filing status, and the number of allowances you claim on your W-4 form. The IRS uses tax brackets to determine the percentage of tax owed.
Social Security Tax: A flat rate of 6.2% on earnings up to an annual limit ($168,600 for 2024).
Medicare Tax: A flat rate of 1.45% on all earnings, with no income limit. Additional Medicare tax may apply for high earners.
Illinois State Income Tax: Illinois has a flat income tax rate. For 2024, the rate is 4.95%. The number of allowances claimed on your Illinois withholding form (IL-W-4) can reduce the amount of tax withheld.
Key Inputs Explained:
Gross Pay: This is your total income before any taxes or deductions are taken out. It's the starting point for all payroll calculations.
Pay Frequency: How often you receive your paycheck (e.g., weekly, bi-weekly, monthly). This affects how taxes are calculated per pay period, especially for progressive federal income tax rates.
Filing Status: Your tax filing status (Single, Married Filing Jointly, Head of Household) impacts the standard deduction and tax brackets used for federal income tax calculations.
Number of Allowances: On your W-4 and IL-W-4 forms, allowances reduce the amount of income tax withheld from your paycheck. More allowances generally mean less tax withheld. For Illinois, the number of allowances is often tied to the number of dependents.
Important Considerations:
This calculator is an estimation tool. Actual net pay may vary due to:
Other payroll deductions like health insurance premiums, 401(k) contributions, union dues, etc.
Specific state tax credits or local taxes not included here.
Changes in tax laws or annual updates to wage bases and tax rates.
The precise calculation of federal withholding can be complex and may involve tax tables not fully replicated here.
For precise payroll figures, always refer to your official pay stub or consult with your employer's HR or payroll department.
function calculateIllinoisPayroll() {
var grossPay = parseFloat(document.getElementById("grossPay").value);
var payFrequency = document.getElementById("payFrequency").value;
var filingStatus = document.getElementById("filingStatus").value;
var allowances = parseInt(document.getElementById("allowances").value);
if (isNaN(grossPay) || grossPay < 0) {
alert("Please enter a valid Gross Pay amount.");
return;
}
if (isNaN(allowances) || allowances < 0) {
allowances = 0; // Default to 0 if invalid
}
var federalTaxableIncome = grossPay; // Simplified for this calculator
var stateTaxableIncome = grossPay; // Simplified for this calculator
// — Federal Tax Calculations (Simplified – Uses a general withholding estimate) —
// This is a VERY simplified estimate. Real withholding uses complex tables.
// We'll use a simplified percentage for demonstration purposes.
var federalIncomeTaxRate = 0.15; // Example placeholder rate, actual rates vary by bracket
if (filingStatus === "married") {
federalIncomeTaxRate = 0.12; // Lower rate example for married
} else if (filingStatus === "headOfHousehold") {
federalIncomeTaxRate = 0.14; // Intermediate rate example
}
// Adjust rate based on allowances (very simplified)
federalIncomeTaxRate -= (allowances * 0.01);
if (federalIncomeTaxRate < 0.05) federalIncomeTaxRate = 0.05; // Minimum rate floor
var federalIncomeTax = federalTaxableIncome * federalIncomeTaxRate;
// — FICA Taxes —
var socialSecurityRate = 0.062;
var medicareRate = 0.0145;
var socialSecurityWageBase = 168600; // For 2024
var socialSecurityTax = 0;
if (grossPay <= socialSecurityWageBase) {
socialSecurityTax = grossPay * socialSecurityRate;
} else {
socialSecurityTax = socialSecurityWageBase * socialSecurityRate;
}
var medicareTax = grossPay * medicareRate;
// — Illinois State Income Tax —
var illinoisIncomeTaxRate = 0.0495; // 4.95% for 2024
// Illinois uses exemptions based on allowances for withholding, not a direct percentage reduction of rate.
// Simplified: we'll just apply the flat rate. For a more accurate calc, IL-W-4 would be needed.
var illinoisIncomeTax = stateTaxableIncome * illinoisIncomeTaxRate;
// — Total Taxes —
var totalTaxes = federalIncomeTax + socialSecurityTax + medicareTax + illinoisIncomeTax;
// — Net Pay —
var netPay = grossPay – totalTaxes;
// Ensure net pay is not negative
if (netPay < 0) {
netPay = 0;
}
// Display Results
document.getElementById("netPayResult").textContent = "$" + netPay.toFixed(2);
document.getElementById("grossPayResultDisplay").textContent = "$" + grossPay.toFixed(2);
document.getElementById("taxResult").textContent = "$" + totalTaxes.toFixed(2);
}