Living and working in Illinois means your paycheck is subject to federal taxes, FICA (Social Security and Medicare), and a flat state income tax. Unlike many other states that use progressive tax brackets, Illinois applies a single rate to all earners.
The Illinois Flat Tax Rate
The current Illinois state income tax rate is 4.95%. This rate is applied to your federally adjusted gross income after subtracting specific Illinois exemptions. For the 2024 tax year, the standard personal exemption is $2,775 per qualifying individual.
FICA Contributions
Federal Insurance Contributions Act (FICA) taxes are mandatory withholdings that fund Social Security and Medicare:
Social Security: 6.2% of your gross pay (up to an annual wage limit of $168,600).
Medicare: 1.45% of your gross pay. High earners (over $200,000) may be subject to an additional 0.9% Medicare tax.
Example Calculation
Suppose you earn an annual salary of $60,000 and are paid bi-weekly (26 periods). Here is how a single paycheck is broken down:
Category
Amount
Gross Bi-Weekly Pay
$2,307.69
Estimated Federal Tax
-$215.00
FICA (Soc Sec + Medicare)
-$176.54
Illinois State Tax (4.95%)
-$109.28
Net Take-Home Pay
$1,806.87
Why Your Paycheck Might Vary
This calculator provides an estimate. Your actual take-home pay may vary based on pre-tax deductions for health insurance, 401(k) contributions, or local municipal taxes. If you reside in specific districts, there may be additional local withholding requirements.
function calculateIllinoisPaycheck() {
var grossPerPeriod = parseFloat(document.getElementById('grossPay').value);
var frequency = parseFloat(document.getElementById('payFrequency').value);
var filingStatus = document.getElementById('filingStatus').value;
var exemptions = parseFloat(document.getElementById('stateExemptions').value) || 0;
if (isNaN(grossPerPeriod) || grossPerPeriod 200000) {
annualMedicare += (annualGross – 200000) * 0.009; // Additional Medicare tax
}
// 2. Federal Income Tax (Simplified 2024 Brackets for Estimation)
var standardDeduction = 14600; // Single
if (filingStatus === "married") standardDeduction = 29200;
if (filingStatus === "head") standardDeduction = 21900;
var taxableFederal = Math.max(0, annualGross – standardDeduction);
var fedTax = 0;
if (filingStatus === "married") {
if (taxableFederal <= 23200) fedTax = taxableFederal * 0.10;
else if (taxableFederal <= 94300) fedTax = 2320 + (taxableFederal – 23200) * 0.12;
else if (taxableFederal <= 201050) fedTax = 10852 + (taxableFederal – 94300) * 0.22;
else if (taxableFederal <= 383900) fedTax = 34337 + (taxableFederal – 201050) * 0.24;
else fedTax = 78221 + (taxableFederal – 383900) * 0.32;
} else {
if (taxableFederal <= 11600) fedTax = taxableFederal * 0.10;
else if (taxableFederal <= 47150) fedTax = 1160 + (taxableFederal – 11600) * 0.12;
else if (taxableFederal <= 100525) fedTax = 5426 + (taxableFederal – 47150) * 0.22;
else if (taxableFederal <= 191950) fedTax = 17168.5 + (taxableFederal – 100525) * 0.24;
else fedTax = 39110.5 + (taxableFederal – 191950) * 0.32;
}
// 3. Illinois State Tax (4.95%)
// IL Exemption is $2,775 per person for 2024
var ilExemptionValue = exemptions * 2775;
var taxableState = Math.max(0, annualGross – ilExemptionValue);
var annualStateTax = taxableState * 0.0495;
// Convert annual figures to pay period
var periodFedTax = fedTax / frequency;
var periodSocSec = annualSocSec / frequency;
var periodMedicare = annualMedicare / frequency;
var periodStateTax = annualStateTax / frequency;
var netPay = grossPerPeriod – periodFedTax – periodSocSec – periodMedicare – periodStateTax;
// Format results
document.getElementById('resGross').innerText = "$" + grossPerPeriod.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resFedTax').innerText = "-$" + periodFedTax.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resSocSec').innerText = "-$" + periodSocSec.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resMedicare').innerText = "-$" + periodMedicare.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resStateTax').innerText = "-$" + periodStateTax.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resNetPay').innerText = "$" + netPay.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resultsArea').style.display = 'block';
// Scroll to results on mobile
document.getElementById('resultsArea').scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}