Illinois has a flat income tax rate, which means every taxpayer pays the same percentage of their income in state income tax, regardless of their income level. This simplifies the tax system compared to progressive tax systems used by many other states. However, understanding how this tax is applied, along with various deductions and credits, is crucial for accurate tax planning.
Illinois Income Tax Rate
As of the current tax year, Illinois imposes a flat income tax rate of 4.95% on individual income. This rate applies to both ordinary income and most types of investment income.
Standard Exemption
Illinois allows taxpayers to claim a standard exemption, which reduces the amount of taxable income. The standard exemption amount for individuals is $2,425 per taxpayer and $2,425 for each dependent. This means that for a single filer, $2,425 of their income is effectively tax-free. For married couples filing jointly, each spouse can claim the exemption, plus exemptions for any dependents.
How the Tax is Calculated
The calculation involves several steps:
Determine Gross Income: This is your total income from all sources before any deductions.
Subtract Exemptions: For the purpose of this calculator, we consider the standard exemption for the filing status.
Single Filer: Subtract $2,425.
Married Filing Jointly: Subtract $4,850 ($2,425 x 2).
Calculate Taxable Income: The amount remaining after subtracting the standard exemption is your taxable income.
Apply the Tax Rate: Multiply the taxable income by the Illinois flat tax rate of 4.95% (0.0495).
Example Calculation
Let's consider a single individual with an annual gross income of $50,000.
Annual Gross Income: $50,000
Standard Exemption (Single): $2,425
Taxable Income: $50,000 – $2,425 = $47,575
Illinois Income Tax: $47,575 * 0.0495 = $2,354.96 (approximately)
Now, let's consider a married couple filing jointly with a combined annual gross income of $80,000.
Annual Gross Income: $80,000
Standard Exemption (Married Filing Jointly): $4,850 ($2,425 x 2)
Taxable Income: $80,000 – $4,850 = $75,150
Illinois Income Tax: $75,150 * 0.0495 = $3,720.93 (approximately)
Important Considerations
This calculator provides an estimate based on the state income tax and standard exemption. It does not account for:
Other potential deductions (e.g., certain business expenses, student loan interest deductions if applicable federally and state-recognized).
Tax credits (e.g., child care credits, property tax credits).
Local income taxes (some Illinois municipalities impose their own income taxes).
Federal income tax.
Illinois has also enacted specific provisions for certain retirement income, which might be exempt.
For precise tax calculations and advice tailored to your specific financial situation, consult with a qualified tax professional or refer to the official Illinois Department of Revenue (IDOR) publications.
var ILLINOIS_TAX_RATE = 0.0495;
var STANDARD_EXEMPTION_SINGLE = 2425;
var STANDARD_EXEMPTION_MARRIED_JOINTLY = 4850; // 2425 * 2
function validateInput(input) {
var value = input.value;
if (isNaN(value) || value < 0) {
input.value = '';
}
}
function calculateIllinoisTax() {
var annualIncomeInput = document.getElementById("annualIncome");
var annualIncome = parseFloat(annualIncomeInput.value);
var filingStatus = document.getElementById("filingStatus").value;
var resultDiv = document.getElementById("result");
resultDiv.style.display = 'none'; // Hide previous result
if (isNaN(annualIncome) || annualIncome < 0) {
alert("Please enter a valid annual gross income.");
return;
}
var exemption;
if (filingStatus === "single") {
exemption = STANDARD_EXEMPTION_SINGLE;
} else if (filingStatus === "married_jointly") {
exemption = STANDARD_EXEMPTION_MARRIED_JOINTLY;
} else {
alert("Please select a valid filing status.");
return;
}
var taxableIncome = annualIncome – exemption;
if (taxableIncome < 0) {
taxableIncome = 0; // Taxable income cannot be negative
}
var illinoisTax = taxableIncome * ILLINOIS_TAX_RATE;
var formattedTax = illinoisTax.toFixed(2);
var formattedTaxableIncome = taxableIncome.toFixed(2);
resultDiv.innerHTML = "Estimated Illinois Income Tax: $" + formattedTax +
"(Based on taxable income of $" + formattedTaxableIncome + ")";
resultDiv.style.display = 'block';
}
function resetCalculator() {
document.getElementById("annualIncome").value = ";
document.getElementById("filingStatus").value = 'single';
document.getElementById("result").style.display = 'none';
document.getElementById("result").innerHTML = ";
}