Illinois Income Tax Calculator 2026

How Illinois taxes income

Illinois uses a single flat rate of 4.95%. Whether you earn $40,000 or $400,000, every dollar of taxable income is taxed at the same percentage. There are no brackets to climb and no threshold to cross.

Illinois has no standard deduction. Instead it allows $2,925 per personal exemption, subtracted from income before the rate is applied.

A flat rate is simpler to predict than a bracketed one, but it is not automatically cheaper. On $85,000, Illinois takes $4,063 — which puts it 44th out of 51 for state income tax at that salary.

How Illinois compares to the other 50

On $85,000, a single filer pays $4,063 in Illinois state income tax. That ranks 44th out of 51 — toward the expensive end.

For scale: 9 states charge nothing at all, and at the other end Oregon takes $6,604 on the same salary.

Income tax is only one of the three big state taxes, though. A state with no income tax often has higher property tax, and a state with high income tax may have low property tax. Ranking states on this one number alone is the most common mistake in these comparisons.

What filing status changes in Illinois

On the same $85,000 salary, the four filing statuses do not produce the same bill. Filing single costs $20,435 in total tax; filing jointly costs $16,405, $4,030 less.

Most of that difference is federal. Illinois's flat 4.95% rate does not change with filing status, though the deduction and exemptions it allows do.

Head of household sits between the two at $17,513, and married filing separately at $20,435. Filing separately is almost never cheaper, but it exists for situations where the tax is not the deciding factor.

What $85,000 looks like in each paycheck

Annual figures are how tax is calculated, but not how anyone experiences it. Spread across the year, $85,000 in Illinois comes to $2,483 every two weeks after federal tax, FICA and Illinois state tax — from a gross of $3,269.

Paid monthly, that is $5,380 landing in your account against $7,083 gross. Paid weekly, $1,242 out of $1,635.

Your actual paycheck will differ from these because employers withhold on a schedule set by your W-4, not on your final tax bill. Over-withholding produces a refund; under-withholding produces a bill in April. Neither changes what you owe.

How to pay less tax in Illinois

The largest lever available to most employees is pre-tax retirement contributions. Putting $5,000 into a traditional 401(k) cuts the $85,000 bill by $1,730 in combined federal and Illinois tax. That money is not gone — it is yours, moved into a retirement account instead of a tax payment.

Push it to $10,000 and the saving rises to $3,460. At the 2026 contribution limit of $23,500, it reaches $7,631.

An HSA works the same way and is stronger still, because contributions avoid Social Security and Medicare as well as income tax. Both reduce your Illinois taxable income too, which is why the saving above is larger than the federal figure alone.

Who pays Illinois income tax

Residents of Illinois pay on all their income, wherever it was earned. Non-residents pay only on income sourced to Illinois — work physically performed there, property located there, business conducted there.

Part-year residents split the year, and the apportionment rules are genuinely fiddly. If you moved during 2026, this calculator will overstate or understate your Illinois bill depending on when you moved — it assumes a full year of residency.

Remote work has made this messier. Some states tax income based on where your employer is rather than where you sit, and a handful still apply a "convenience of the employer" rule. If you work across a state line, that question is worth answering before April.

Retirement income in Illinois

Illinois does not tax Social Security. It is one of 42 states plus the District that exempt benefits entirely — only eight still reach them in 2026.

Illinois exempts pensions, 401(k) and IRA distributions in full, with no age test and no income limit — unusual for a state that taxes wages.

Military retirement pay is fully exempt in Illinois. That puts it with the great majority of states — since California brought in a partial exclusion for 2025, the District of Columbia is the only place left that taxes military retirement in full.

The calculator above does not apply any of this — it models salary income with the standard deduction. If a meaningful share of your income is retirement income, treat that figure as an upper bound.

What this Illinois calculator leaves out

Being specific about the gaps is more useful than claiming there are none. This figure covers federal income tax, Social Security and Medicare, and Illinois state income tax on salary income, using the standard deduction.

itemised deductions beyond the standard one, credits such as the Child Tax Credit and the Earned Income Tax Credit, capital gains, dividends and other investment income, self-employment income and the tax that comes with it, the Alternative Minimum Tax — none of these are in the number above.

If your situation includes any of them, the result here is a starting point, not an answer. That is also why we publish which state figures we have checked against Illinois Department of Revenue and which we have not.

What has changed, and what changes next, in Illinois

We have not yet loaded a rate history for Illinois. Twenty-six states have cut income tax rates since 2021 and seven have moved from brackets to a single rate, so the direction of travel nationally is downward.

Where Illinois sits against similar states

On $85,000, the states closest to Illinois are Virginia ($4,073), Massachusetts ($4,030), New York ($3,993). If you are weighing a move between any of these, state income tax is not the deciding factor — the gap is smaller than a single pay rise.

The nearest states that charge less are Massachusetts ($4,030), New York ($3,993), Alabama ($3,985) — a saving of up to $78 a year at this salary.

Just above sit Virginia ($4,073), District of Columbia ($4,257), Minnesota ($4,257). And Oregon takes $6,604, $2,541 more than Illinois on the same salary.

What five different salaries actually cost in Illinois

The single most useful thing to see is how the total moves with income, because it does not move in a straight line. Here is the same calculation at five salaries, single filer, standard deduction:

$45,000 → $8,745 in tax (19.43%), leaving $36,255. $65,000 → $13,665 in tax (21.02%), leaving $51,335. $85,000 → $20,435 in tax (24.04%), leaving $64,565. $120,000 → $32,545 in tax (27.12%), leaving $87,455. $185,000 → $56,268 in tax (30.42%), leaving $128,732.

Between $45,000 and $185,000 the total rate rises by 11.0 points — from 19.43% to 30.42%. That is a smaller jump than most people expect from a salary that has more than quadrupled, and the reason is structural: federal brackets are marginal, so a raise never re-taxes what you already earned, and Social Security stops entirely above $184,500.

Look at the FICA line specifically. At $45,000 it is $3,443, which is 7.65% of gross — more than the $3,220 of federal income tax at that level. At $185,000 it is $14,122, or 7.63%. FICA is the tax that weighs most on modest incomes and least on large ones, and it is the one nobody talks about.

Your marginal rate is not what you pay

On $85,000 in Illinois the federal marginal rate is 22.00% — that is what the next dollar costs. What the whole salary actually cost in federal income tax is 11.61%, or $9,870. The gap between those two numbers is the single most misunderstood thing in US tax.

The reason is that brackets are marginal, not cliffs. Only the slice of income inside a bracket is taxed at that bracket's rate. The first $16,100 is not taxed at all, the next slice at 10.00%, and so on up. A pay rise that "pushes you into a higher bracket" never reduces your take-home — that fear is the practical cost of the confusion.

Illinois sidesteps the whole question with a single flat rate of 4.95%, so its marginal and effective rates are the same.

And there is a third rate that matters more than either: 24.04%, which is everything — federal, FICA, Illinois — as a share of gross. That is what actually left your pay. Never compare it against a marginal rate; they measure different things and the comparison suggests an error that is not there.

What a single flat rate does that brackets do not

Illinois charges a single rate of 4.95% rather than running brackets. Fifteen states now do this, and seven of them moved to it since 2021 — it is the clearest trend in US state tax policy of the past five years.

The practical difference is predictability. Your marginal and effective state rates are the same number, so a raise costs exactly what the rate says and there is no bracket to worry about crossing. On $85,000 the state bill is $4,063.

The distributional consequence is the argument against it. A flat rate takes the same proportion from a $45,000 salary as from a $400,000 one, which means it is a heavier burden relative to what a modest household can absorb, and several flat states offset it with an exempt band rather than a deduction.

Watch for the exempt band specifically, because compiled sources miss it constantly. Ohio and Mississippi both charge what looks like a flat rate but tax nothing below a threshold — we found sources overstating Ohio's bill by 43% for exactly that reason. A "flat" state is not always flat from the first dollar.

What your next $10,000 is actually worth here

Going from $85,000 to $95,000 in Illinois raises your tax by $3,460, so you keep $6,540 of the $10,000 — an effective rate on the raise of 34.60%. That is the number worth having in a salary negotiation, and it is not the same as either your bracket or your average rate.

Notice that it is higher than your overall effective rate of 24.04%. New income is always taxed at the top, so the marginal cost of a raise exceeds the average cost of everything you already earn. That is the whole point of a progressive system, and it is also why a bonus feels more heavily taxed than a salary — it is stacked on top.

Bonuses have a wrinkle of their own. Employers often withhold them at a flat supplemental rate rather than at your actual marginal rate, which can take more or less than you owe. It comes out right at filing either way, but it explains why a bonus payslip so often looks wrong.

With no local income tax in Illinois, the cost of the raise is entirely federal, FICA and Illinois.

Five ways this calculation goes wrong

Adding FICA to the withholding. Boxes 4 and 6 of your W-2 are Social Security and Medicare. They are not advance payments of income tax and never come back as a refund. Only box 2 (federal) and box 17 (state) belong in a refund calculation, and including the others overstates it by thousands.

Comparing the effective rate against the marginal rate. Here that would mean setting 24.04% against 22.00% and concluding something has gone wrong. Nothing has: the first includes payroll and state tax, the second is federal income tax on the next dollar. They measure different things.

Assuming a flat state is flat from the first dollar. Ohio taxes nothing below $27,350 of taxable income and Mississippi nothing below $10,000, yet both are widely published as simple flat rates. That single omission overstated Ohio's bill by 43% in the sources we checked.

Assuming your city takes a cut. Illinois does not levy an income tax, and only fifteen states permit any city to. Budgeting for one that does not exist is the mirror of the previous mistake.

Using last year's figures. Bracket thresholds, the standard deduction and several state rates are indexed and move every January. Worse, states backdate: Georgia cut its rate in May 2026 with effect from 1 January, so a table published in April was correct when written and wrong by summer. That is why every figure on this site carries the date it was checked.

Deadlines and what you actually have to file in Illinois

Federal returns for 2026 are due on 15 April 2027. An extension gives you until 15 October to FILE, but not to PAY — anything owed still accrues interest from April, which is the part people misread. If you expect to owe more than $1,000 beyond withholding, the IRS expects quarterly estimated payments rather than a single settlement.

Illinois generally follows the federal calendar, and most states accept the federal extension automatically rather than requiring their own form. Check before assuming: a handful require a separate request, and the penalty for getting it wrong is charged on a bill you may not know you have.

With no local income tax there is no third return to worry about, which is worth something on its own: in states like Ohio and Pennsylvania a working household can face three separate filings a year.

Whatever your situation, the figures on this page are for planning. They assume a salaried filer taking the standard deduction, and they do not model itemised deductions, self-employment income, capital gains, or credits such as the EITC that can change the answer substantially.

Where the Illinois figures come from

Federal brackets and the standard deduction come from the IRS Revenue Procedure for 2026, read off the document itself rather than a summary of it.

The Illinois figures have been checked against Illinois Department of Revenue. Where our original data was wrong, the page says so rather than quietly fixing it — because a calculator that has never admitted an error is either new or not looking.

Every figure carries the date we last verified it, and the full log is published rather than kept internally.

Illinois income tax questions

Does Illinois have a state income tax?

Yes. Illinois taxes income at a flat 4.95%, the same rate at every income level.

How much is $85,000 after tax in Illinois?

A single filer earning $85,000 in Illinois keeps $64,565 for 2026. That is after $9,870 in federal income tax, $6,503 in Social Security and Medicare, and $4,063 in Illinois state tax — an effective rate of 24.04% across everything.

What is the top Illinois tax rate?

Illinois has a single rate of 4.95%, so there is no separate top rate.

Why is my Illinois tax bill different from this estimate?

This estimate uses the standard deduction and no credits beyond it. Real returns often include state-specific credits, itemised deductions, retirement income exclusions. It is built for planning, not for filing.

How much do I take home per paycheck on $85,000 in Illinois?

Paid every two weeks, $2,483 after federal tax, FICA and Illinois tax, from a gross of $3,269. Paid monthly, $5,380.

Does contributing to a 401(k) reduce my Illinois tax?

Yes. Traditional 401(k) contributions come out before both federal and Illinois income tax. On $85,000, contributing $10,000 cuts your combined bill by $3,460.

Is it cheaper to file jointly in Illinois?

On $85,000, filing jointly costs $16,405 against $20,435 filing single — $4,030 less. Whether that holds for you depends on both incomes, not just one.